1Z Number: 1Z0-117 Passing Score: 660 Time Limit: 150 min File Version: 1.0.

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1 1Z0-117 Number: 1Z0-117 Passing Score: 660 Time Limit: 150 min File Version: 1.0

2 Exam A QUESTION 1 Examine the query and its execution plan: Which statement is true regarding the execution plan? A. This query first fetches rows from the CUSTOMERS table that satisfy the conditions, and then the join return NULL from the CUSTOMER_ID column when it does not find any corresponding rows in the ORDERS table. B. The query fetches rows from CUSTOMERS and ORDERS table simultaneously, and filters the rows that satisfy the conditions from the resultset. C. The query first fetches rows from the ORDERS table that satisfy the conditions, and then the join returns NULL form CUSTOMER_ID column when it does not find any corresponding rows in the CUSTOMERS table. D. The query first joins rows from the CUSTOMERS and ORDERS tables and returns NULL for the ORDERS table columns when it does not find any corresponding rows in the ORDERS table, and then fetches the rows that satisfy the conditions from the result set. Correct Answer: A /Reference: QUESTION 2 Which three statements are true about histograms? A. They capture the distribution of different values in an index for better selectivity estimates. B. They can be used only with indexed columns.

3 C. They provide metadata about distribution of and occurrences of values in a table column. D. They provide improved selectivity estimates in the presence of data skew, resulting in execution plans with uniform distribution. E. They help the optimizer in deciding whether to use an index or a full table scan. F. They help the optimizer to determine the fastest table join order. Correct Answer: CEF /Reference: C:A histogram is a frequency distribution (metadata) that describes the distribution of data values within a table. E:It's well established that histograms are very useful for helping the optimizer choose between a full-scan and and index-scan. F:Histograms may help the Oracle optimizer in deciding whether to use an index vs. a full-table scan (where index values are skewed) or help the optimizer determine the fastest table join order. For determining the best table join order, the WHERE clause of the query can be inspected along with the execution plan for the original query. If the cardinality of the table is too-high, then histograms on the most selective column in the WHERE clause will tip-off the optimizer and change the table join order. Note: *The Oracle Query Optimizer uses histograms to predict better query plans. The ANALYZE command or DBMS_STATS package can be used to compute these histograms. Incorrect: B:Histograms are NOT just for indexed columns. Adding a histogram to an un-indexed column that is used in a where clause can improve performance. D:Histograms Opportunities Any column used in a where clause with skewed data Columns that are not queried all the time Reduced overhead for insert, update, delete QUESTION 3 View the exhibit and examine the query and its execution plan from the PLAN_TABLE. Which statement is true about the execution? Exhibit:

4 A. The row with the ID column having the value 0 is the first step execution plan. B. Rows are fetched from the indexes on the PRODUCTS table and from the SALES table using full table scan simultaneously, and then hashed into memory. C. Rows are fetched from the SALES table, and then a hash join operator joins with rows fetched from indexes on the PRODUCTS table. D. All the partitions of the SALES table are read in parallel. Correct Answer: C /Reference: QUESTION 4

5 Which four statements are correct about communication between parallel execution process? A. The number of logical pathways between parallel execution producers and consumers depends on the degree parallelism. B. The shared pool can be used for parallel execution messages buffers. C. The large pool can be used for parallel execution messages buffers. D. The buffer cache can be used for parallel execution message buffers. E. Communication between parallel execution processes is never required if a query uses full partition-wise joins. F. Each parallel execution process has an additional connection to the parallel execution coordinator. Correct Answer: ABEF /Reference: A:Note that the degree of parallelism applies directly only to intra-operation parallelism. If inter-operation parallelism is possible, the total number of parallel execution servers for a statement can be twice the specified degree of parallelism. No more than two sets of parallel execution servers can run simultaneously. Each set of parallel execution servers may process multiple operations. Only two sets of parallel execution servers need to be active to guarantee optimal inter-operation parallelism. B:By default, Oracle allocates parallel execution buffers from the shared pool. F:When executing a parallel operation, the parallel execution coordinator obtains parallel execution servers from the pool and assigns them to the operation. If necessary, Oracle can create additional parallel execution servers for the operation. These parallel execution servers remain with the operation throughout job execution, then become available for other operations. After the statement has been processed completely, the parallel execution servers return to the pool. Reference: OracleDatabase Data Warehousing Guide,Using Parallel Execution QUESTION 5 You have enabled DML by issuing: ALTER session ENABLE PARALLEL DML; The PARELLEL_DEGREE_POLICY initialization parameter is set to AUTO. Which two options true about DML statements for which parallel execution is requested? A. Statements for which PDML is requested will execute serially estimated time is less than the time specified by the PARALLEL_MIN_THRESHOLD parameter. B. Statements for which PDML is requested will be queued if the number of busy parallel execution servers greater than PARALLEL_MIN_SERVERS parameter. C. Statements for which PDML is requested will always execute in parallel if estimated execution in parallel if estimated execution time is greater than the time specified bythe PARELLEL_MIN_TIME_THRESHOLD parameter. D. Statements for which PDML is requested will be queued if the number of busy parallel execution servers is greater than PARELLEL_SERVERS_TARGET parameter. E. Statement for which PDML is requested will be queued if the number of busy parallel execution servers is greater than PARELLEL_DEGREE_LIMIT parameter. Correct Answer: CD /Reference: C:PARALLEL_MIN_TIME_THRESHOLD specifies the minimum execution time a statement should have before the statement is considered for automatic degree of parallelism. By

6 default, this is set to 30 seconds. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. D:PARALLEL_SERVERS_TARGET specifies the number of parallel server processes allowed to run parallel statements before statement queuing will be used. When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle will queue SQL statements that require parallel execution, if the necessary parallel server processes are not available. Statement queuing will begin once the number of parallel server processes active on the system is equal to or greater than PARALLEL_SERVER_TARGET. Note: *PARALLEL_DEGREE_POLICY specifies whether or not automatic degree of Parallelism, statement queuing, and in-memory parallel execution will be enabled. AUTO Enables automatic degree of parallelism, statement queuing, and in-memory parallel execution. * PARALLEL_MIN_SERVERS specifies the minimum number of parallel execution processes for the instance. This value is the number of parallel execution processes Oracle creates when the instance is started. Reference: OracleDatabase Reference;PARALLEL_SERVERS_TARGET QUESTION 6 Examine Exhibit1 to view the query and its AUTOTRACE output. Which two statements are true about tracing? Exhibit:

7 A. The displayed plan will be stored in PLAN_TABLE. B. Subsequent execution of this statement will use the displayed plan that is stored in v$sql. C. The displayed plan may not necessarily be used by the optimizer.

8 D. The query will not fetch any rows; it will display only the execution plan and statistics. E. The execution plan generated can be viewed from v$sqlarea. Correct Answer: AC /Reference: A:The PLAN_TABLE is automatically created as a public synonym to a global temporary table. This temporary table holds the output of EXPLAIN PLAN statements for all users. PLAN_TABLE is the default sample output table into which the EXPLAIN PLAN statement inserts rows describing execution plans Incorrect: B: V$SQL lists statistics on shared SQL area without the GROUP BY clause and contains one row for each child of the original SQL text entered. Statistics displayed in V$SQL are normally updated at the end of query execution. However, for long running queries, they are updated every 5 seconds. This makes it easy to see the impact of long running SQL statements while they are still in progress. D:autotrace traceonly Displays execution plan and statistics without displaying the returned rows. This option should be used when a large result set is expected. E:V$SQLAREA lists statistics on shared SQL area and contains one row per SQL string. It provides statistics on SQL statements that are in memory, parsed, and ready for execution. Note: *The autotrace provides instantaneous feedback including the returned rows, execution plan, and statistics. The user doesn t need to be concerned about trace file locations and formatting since the output is displayed instantly on the screen. This is very important data that can be used to tune the SQL statement. *SET AUTOTRACE ON The AUTOTRACE report includes both the optimizer execution path and the SQL statement execution statistics. SET AUTOTRACE TRACEONLY Similar to SET AUTOTRACE ON, but suppresses the printing of the user's query output, if any. If STATISTICS is enabled, query data is still fetched, but not printed. QUESTION 7 Which two types of column filtering may benefit from partition pruning? A. Equally operates on range-partitioned tables. B. In-list operators on system-partitioned tables C. Equality operators on system-partitioned tables D. Operators on range-partitioned tables E. Greater than operators on hash-partitioned tables Correct Answer: AD /Reference: The query optimizer can perform pruning whenever a WHERE condition can be reduced to either one of the following two cases: partition_column = constant partition_column IN (constant1, constant2,..., constantn)

9 In the first case, the optimizer simply evaluates the partitioning expression for the value given, determines which partition contains that value, and scans only this partition. In many cases, the equal sign can be replaced with another arithmetic comparison, including <, >, <=, >=, and <>. Some queries using BETWEEN in the WHERE clause can also take advantage of partition pruning. Note: *The core concept behind partition pruning is relatively simple, and can be described as Do not scan partitions where there can be no matching values. When the optimizer can make use of partition pruning in performing a query, execution of the query can be an order of magnitude faster than the same query against a nonpartitioned table containing the same column definitions and data. * Example: Suppose that you have a partitioned table t1 defined by this statement: CREATE TABLE t1 ( fname VARCHAR(50) NOT NULL, lname VARCHAR(50) NOT NULL, region_code TINYINT UNSIGNED NOT NULL, dob DATE NOT NULL ) PARTITION BY RANGE( region_code ) ( PARTITION p0 VALUES LESS THAN (64), PARTITION p1 VALUES LESS THAN (128), PARTITION p2 VALUES LESS THAN (192), PARTITION p3 VALUES LESS THAN MAXVALUE ); Consider the case where you wish to obtain results from a query such as this one: SELECT fname, lname, region_code, dob FROM t1 WHERE region_code > 125 AND region_code < 130; It is easy to see that none of the rows which ought to be returned will be in either of the partitions p0 or p3; that is, we need to search only in partitions p1 and p2 to find matching rows. By doingso, it is possible to expend much less time and effort in finding matching rows than would be required to scan all partitions in the table. This cutting away of unneeded partitions is known as pruning. QUESTION 8 Which two statements about In-Memory Parallel Execution are true? A. It can be configured using the Database Resource Manager. B. It increases the number of duplicate block images in the global buffer cache. C. It requires setting PARALLEL_DEGREE_POLICY to LIMITED. D. Objects selected for In-Memory Parallel Execution have blocks mapped to specific RAC instances. E. It requires setting PARALLEL_DEGREE_POLICY to AUTO F. Objects selected for In-Memory Parallel Execution must be partitioned tables or indexes. Correct Answer: DE /Reference: D, E:In-Memory Parallel Execution When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle Database decides if

10 an object that is accessed using parallel execution would benefit from being cached in the SGA (also called the buffer cache). The decision to cache an object is based on a well-defined set of heuristics including the size of the object and frequency on which it is accessed. In an Oracle RAC environment, Oracle Database maps pieces of the object into each of the buffer caches on the active instances. By creating this mapping, Oracle Database automatically knows which buffer cache to access to find different parts or pieces of the object. Using this information, Oracle Database prevents multiple instances from reading the same information from disk over and over again, thus maximizing the amount of memory that can cache objects. If the size of the object is larger than the size of the buffer cache (single instance) or the size of the buffer cache multiplied by the number of active instances in an Oracle RAC cluster, then the object is read using directpath reads. E:PARALLEL_DEGREE_POLICY specifies whether or not automatic degree of Parallelism, statement queuing, and in-memory parallel execution will be enabled. AUTO Enables automatic degree of parallelism, statement queuing, and in-memory parallel execution. Incorrect: C: LIMITED Enables automatic degree of parallelism for some statements but statement queuing and inmemory Parallel Execution are disabled. Automatic degree of parallelism is only applied to those statements that access tables or indexes decorated explicitly with the PARALLEL clause. Tables and indexes that have a degree of parallelism specified will use that degree of parallelism. Reference:Oracle Database VLDB and Partitioning Guide11g,How Parallel Execution Works QUESTION 9 Which two are benefits of In-Memory Parallel Execution? A. Reduction in the duplication of block images across multiple buffer caches B. Reduction in CPU utilization C. Reduction in the number of blocks accessed D. Reduction in physical I/O for parallel queries E. Ability to exploit parallel execution servers on remote instance Correct Answer: AC /Reference: Note:In-Memory Parallel Execution When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle Database decides if an object that is accessed using parallel execution would benefit from being cached in the SGA (also called the buffer cache). The decision to cache an object is based on a well-defined set of heuristics including the size of the object and frequency on which it is accessed. In an Oracle RAC environment, Oracle Database maps pieces of the object into each of the buffer caches on the active instances. By creating this mapping, Oracle Database automatically knows which buffer cache to access to find different parts or pieces of the object. Using this information, Oracle Database prevents multiple instances from reading the same information from disk over and over again, thus maximizing the amount of memory that can cache objects. If the size of the object is larger than the size of the buffer cache (single instance) or the size of the buffer cache multiplied by the number of active instances in an Oracle RAC cluster, then the object is read using directpath reads. Reference:Oracle Database VLDB and Partitioning Guide11g,How Parallel Execution Works QUESTION 10

11 You plan to bulk load data INSERT INTO... SELECT FROM statements. Which two situations benefit from parallel INSERT operations on tables that have no materialized views defined on them? A. Direct path insert of a million rows into a partitioned, index-organizedtable containing one millionrows anda conventional B*treesecondary index. B. Direct path insert of a million rows into a partitioned, index-organized table containing 10 rows and a bitmapped secondary index. C. Direct path insert of 10 rows into a partitioned, index-organized table containing one million rows and conventional B* tree secondary index. D. Direct path insert of 10 rows into a partitioned, index-organized table containing10rowsand a bitmapped secondary index E. Conventionalpath insert of a million rows into a nonpartitioned, heap-organized containing 10 rows and having a conventional B* tree index. F. Conventional path insert of 10 rows into a nonpartitioned, heap-organized table one million rows and a bitmapped index. Correct Answer: AB /Reference: Note: *A materialized view is a database object that contains the results of a query. *You can use the INSERT statement to insert data into a table, partition, or view in two ways: conventional INSERTand direct-path INSERT. * With direct-path INSERT, the database appends the inserted data after existing data in the table. Data is written directly into datafiles, bypassing the buffer cache. Free space in the existing data is not reused. This alternative enhances performance during insert operations and is similar to the functionality of the Oracle direct-path loader utility, SQL*Loader. When you insert into a table that has been created in parallel mode, direct-path INSERT is the default. * Direct-path INSERT is not supported for an index-organized table (IOT) if it is not partitioned, if it has a mapping table, or if it is reference by a materialized view. * When you issue a conventional INSERT statement, Oracle Database reuses free space in the table into which you are inserting and maintains referential integrity constraints * Conventional INSERT always generates maximal redo and undo for changes to both data and metadata, regardless of the logging setting of the table and the archivelog and force logging settings of the database QUESTION 11 Which are the two prerequisites for enabling star transformation on queries? A. The STAR_TRANSFORMATION_ENABLED parameter should be set to TRUE or TEMP_DISABLE. B. A B-tree index should be built on each of the foreign key columns of the fact table(s), C. A bitmap index should be built on each of the primary key columns of the fact table(s). D. A bitmap index should be built on each of the foreign key columns of the fact table(s). E. A bitmap index must exist on all the columns that are used in the filter predicates of the query. Correct Answer: AE /Reference: A:Enabling the transformation E:Star transformation is essentially about adding subquery predicates corresponding to the

12 constraint dimensions. These subquery predicates are referred to as bitmap semi-join predicates. The transformation is performed when there are indexes on the fact join columns (s.timeid, s.custid...). By driving bitmap AND and OR operations (bitmaps can be from bitmap indexes or generated from regular B-Tree indexes) of the key values supplied by the subqueries, only the relevant rows from the fact table need to be retrieved. If the filters on the dimension tables filter out a lot of data, this can be much more efficient than a full table scan on the fact table. After the relevant rows have been retrieved from the fact table, they may need to be joined back to the dimension tables, using the original predicates. In some cases, the join back can be eliminated. Star transformation is controlled by the star_transformation_enabled parameter. The parameter takes 3 values. TRUE - The Oracle optimizer performs transformation by identifying fact and constraint dimension tables automatically. This is done in a cost-based manner, i.e. the transformation is performed only if the cost of the transformed plan is lower than the non-transformed plan. Also the optimizer will attempt temporary table transformation automatically whenever materialization improves performance. FALSE - The transformation is not tried. TEMP_DISABLE - This value has similar behavior as TRUE except that temporary table transformation is not tried. The default value of the parameter is FALSE. You have to change the parameter value and create indexes on the joining columns of the fact table to take advantage of this transformation. Reference:Optimizer Transformations: Star Transformation QUESTION 12 An application accessing your database got the following error in response to SQL query: ORA-12827: insufficient parallel query slaves available View the parallel parameters for your instance: No hints are used and the session use default parallel settings. What four changes could you make to help avoid the error and ensure that the query executes in parallel?

13 A. Set PARELLEL_DEGREE_POLICY to AUTO B. Increase the value of PARELLEL_MAX_SERVERS. C. Increase PARELLEL_SERVERS_TARGET. D. Decrease PARELLEL_MIN_PERCENT. E. Increase PARELLEL_MIN_SERVERS. F. Decrease PARELLEL_MIN_TIME_THRESHOLD. G. Increase PARELLEL MIN_TIME_THRESHOLD. Correct Answer: ACDG /Reference: C:PARALLEL_SERVERS_TARGET specifies the number of parallel server processes allowed to run parallel statements before statement queuing will be used. When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle will queue SQL statements thatrequire parallel execution, if the necessary parallel server processes are not available. Statement queuing will begin once the number of parallel server processes active on the system is equal to or greater than PARALLEL_SERVER_TARGET. By default, PARALLEL_SERVER_TARGET is set lower than the maximum number of parallel server processes allowed on the system (PARALLEL_MAX_SERVERS) to ensure each parallel statement will get all of the parallel server resources required and to prevent overloading the system with parallel server processes. D: Note:ORA-12827:insufficient parallel query slaves available Cause:PARALLEL_MIN_PERCENT parameter was specified and fewer than minimum slaves were acquired Action:either re-execute query with lower PARALLEL_MIN_PERCENT or wait until some running queries are completed, thus freeing up slaves A, G:PARALLEL_MIN_TIME_THRESHOLD specifies the minimum execution time a statement should have before the statement is considered for automatic degree of parallelism. By default, this is set to 30 seconds. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. QUESTION 13 Examine the Exhibit 1 to view the structure of and indexes for EMPLOYEES and DEPARTMENTS tables.

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15 Which three statements are true regarding the execution plan? Exhibit:

16 A. The view operator collects all rows from a query block before they can be processed but higher operations in the plan. B. The in-line query in the select list is processed as a view and then joined. C. The optimizer pushes the equality predicate into the view to satisfy the join condition. D. The optimizer chooses sort-merge join because sorting is required for the join equality predicate. E. The optimizer chooses sort-merge join as a join method because an equality predicate is used for joining the tables. Correct Answer: BCE /Reference: QUESTION 14 In Your Database, The Cursor_Shareing Parameter is set to EXACT. In the Employees table, the data is significantly skewed in the DEPTNO column. The value 10 is found in 97% of rows. Examine the following command and out put. Which three statements are correct? A. The DEPTNO column will become bind aware once histogram statistics are collected. B. The value for the bind variable will considered by the optimizer to determine the execution plan. C. The same execution plan will alwaysbe used irrespective of the bind variable value. D. The instance collects statistics and based on the pattern of executions creates a histogram on the column containing the bind value. E. Bind peeking will take place only for the first execution of the statement and subsequent execution will use the same plan. Correct Answer: ABD

17 /Reference: * We here see that the cursor is marked as bind sensitive (IS_BIND_SENis Y). *In 11g, the optimizer has been enhanced to allow multiple execution plans to be used for a single statement that uses bind variables. This ensures that the best execution plan will be used depending on the bind value. * A cursor is marked bind sensitive if the optimizer believes the optimal plan may depend on the value of the bind variable. When a cursor is marked bind sensitive, Oracle monitorsthe behavior of the cursor using different bind values, to determine if a different plan for different bind values is called for. * (B, not C):A cursor is marked bind sensitive if the optimizer believes the optimal plan may depend on the value of the bind variable. When a cursor is marked bind sensitive, Oracle monitors the behavior of the cursor using different bind values, to determine if a different plan for different bind values is called for. Note:Setting CURSOR_SHARING to EXACT allows SQL statements to share the SQL area only when their texts match exactly. This is the default behavior. Using this setting, similar statements cannot shared; only textually exact statements can be shared. Reference:Why are there more cursors in 11g for my query containing bind variables? QUESTION 15 You created a SQL Tuning Set (STS) containing resource-intensive SQL statements. You plan to run the SQL Tuning Advisor. Which two types of recommendations can be provided by the SQL Tuning Advisor? A. Semantic restructuring for each SQL statement B. Gathering missing or stale statistics at the schema level for the entire workload C. Creating a materialized view to benefit from query rewrite for the entire workload D. Gathering missing or stale statistics for objects used by the statements. E. Creating a partition table to benefit from partition pruning for each statement Correct Answer: AD /Reference: The output of the SQL Tuning Advisor is in the form of an advice or recommendations, along with a rationale for each recommendation and its expected benefit. The recommendation relates to collection of statistics on objects( D), creation of new indexes, restructuring of the SQL statement(a), or creation of a SQL profile. You can choose to accept the recommendation to complete the tuning of the SQL statements. Note: *A SQL Tuning Set can be used as input to the SQL Tuning Advisor, which performs automatic tuning of the SQL statements based on other input parameters specified by the user. *A SQL Tuning Set (STS) is a database object that includes one or more SQL statements along with their execution statistics and execution context, and could include a user priority ranking. The SQL statements can be loaded into a SQL Tuning Set from different SQL sources, such as the Automatic Workload Repository, the cursor cache, or custom SQL provided by the user. Reference: OracleDatabase Performance Tuning Guide11g,SQL Tuning Advisor QUESTION 16 When would bind peeking be done for queries that vary only in values used in the WHERE clause?

18 A. When the column used in the WHERE clause has evenly distributed data and histogram exists on that column. B. When the column used in the WHERE clause has evenly distributed data and index exists on that column. C. When the column used in the WHERE clause has non uniform distribution of data, uses a bind variable, and no histogram exists for the column. D. When the column used in the WHERE clause has non uniform distribution of data and histogram exists for the column. Correct Answer: B /Reference: QUESTION 17 Which type of SQL statement would be selected for tuning by the automatic SQL framework? A. Serial queries that are among the costliest in any or all of the four categories: the past week, any day in the past week, any hour in the past week, or single response, and have the potential for improvement B. Serial queries that have been tuned within the last 30days and have been SQL profiled by the SQL tuning Advisor. C. Serial and parallel queries that top the AWR Top SQL in the past week only and have been SQL profiled by the SQL Tuning Advisor. D. Serial queries that top the AWR Top SQL in the past week only and whose poor performance can be traced to concurrency issues. E. Serial and parallel queries that are among the costliest in any or all of the four categories: the past week, and day in the past week, any hour in the past week, or a single response, and that can benefit from access method changes. Correct Answer: E /Reference: The Automatic Tuning Optimizer is meant to be used for complex and high-load SQL statements that have non-trivial impact on the entire system. The Automatic Database Diagnostic Monitor (ADDM) proactively identifies high-load SQL statements which are good candidates for SQL tuning. Note: *When SQL statements are executed by the Oracle database, the query optimizer is used to generate the execution plans of the SQL statements. The query optimizer operates in two modes: a normal mode and a tuning mode. In normal mode, the optimizer compiles the SQL and generates an execution plan. The normal mode of the optimizer generates a reasonable execution plan for the vast majority of SQL statements. Under normal mode, the optimizer operates with very strict time constraints, usually a fraction of a second, during which it must find a good execution plan. In tuning mode, the optimizer performs additional analysis to check whether the execution plan produced under normal mode can be improved further. The output of the query optimizer is not an execution plan, but a series of actions, along with their rationale and expected benefit for producing a significantly superior plan. When running in the tuning mode, the optimizer is referred to as the Automatic Tuning Optimizer.

19 Reference: OracleDatabase Performance Tuning Guide,Automatic SQL Tuning QUESTION 18 You instance has these parameter settings: Which three statements are true about these settings if no hints are used in a SQL statement? A. A statement estimated for more than 10 seconds always has its degree of parallelism computed automatically. B. A statement with a computed degree of parallelism greater than 8 will be queued for a maximum of 10 seconds. C. A statement that executes for more than 10 seconds always has its degree of parallelism computed automatically. D. A statement with a computed degree of parallelism greater than 8 will raise an error. E. A statement with any computed degree of parallelism will be queued if the number of busy parallel execution processes exceeds 64. F. A statement with a computed degree of parallelism of 20 will be queued if the number of available parallel execution processes is less 5. Correct Answer: CEF /Reference: C (not A): PARALLEL_MIN_TIME_THRESHOLD specifies the minimum execution time a statement should have before the statement is considered for automatic degree of parallelism. By default, this is set to 30 seconds. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. PARALLEL_DEGREE_LIMIT integer A numeric value for this parameter specifies the maximum degree of parallelism the optimizer can choose for a SQL statement when automatic degree of parallelism is active. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. E:PARALLEL_SERVERS_TARGET specifies the number of parallel server processes allowed to run parallel statements before statement queuing will be used. When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle will queue SQL statements that require parallel execution, if the necessary parallel server processes are not available. Statement queuing will begin once the number of parallel server processes active on the system is equal to or greater than PARALLEL_SERVER_TARGET. F:PARALELL_MIN_MINPERCENT PARALLEL_MIN_PERCENT operates in conjunction with PARALLEL_MAX_SERVERS and PARALLEL_MIN_SERVERS. It lets you specify the minimum percentage of parallel execution processes (of the value of PARALLEL_MAX_SERVERS) required for parallel execution. Setting this parameter ensures

20 that parallel operations will not execute sequentially unless adequate resources are available. The default value of 0 means that no minimum percentage of processes has been set. Consider the following settings: PARALLEL_MIN_PERCENT = 50 PARALLEL_MIN_SERVERS = 5 PARALLEL_MAX_SERVERS = 10 If 8 of the 10 parallel execution processes are busy, only 2 processes are available. If you then request a query with a degree of parallelism of 8, the minimum 50% will not be met. Note:With automatic degree of parallelism, Oracle automatically decides whether or not a statement should execute in parallel and what degree of parallelism the statement should use. The optimizer automatically determines the degree of parallelism for a statement based on the resource requirements of the statement. However, the optimizer will limit the degree of parallelism used to ensure parallel server processes do not flood the system. This limit is enforced by PARALLEL_DEGREE_LIMIT. Values: CPU IO integer A numeric value for this parameter specifies the maximum degree of parallelism the optimizer can choose for a SQL statement when automatic degree of parallelism is active. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. Reference: PARALLEL_MIN_TIME_THRESHOLD PARALLEL_DEGREE_LIMIT PARALELL_MIN_MINPERCENT PARALELL_SERVERS_TARGET QUESTION 19 Examine the following SQL statement: Examine the exhibit to view the execution plan. Which statement is true about the execution plan? Exhibit:

21 A. The EXPLAIN PLAN generates the execution plan and stores it in c$sql_plan after executing the query. Subsequent executions will use the same plan. B. The EXPLAIN PLAN generates the execution plan and stores it in PLAN_TABLE without executing the query. Subsequent executions will always use the same plan. C. The row with the ID 3 is the first step executed in the execution plan. D. The row with the ID 0 is the first step executed in the execution plan. E. The rows with the ID 3 and 4 are executed simultaneously. Correct Answer: E /Reference: Note the other_tag parallel in the execution plan. Note: Within the Oracle plan_table, we see that Oracle keeps the parallelism in a column called other_tag. The other_tag column will tell you the type of parallel operation that is being performed within your query. For parallel queries, it is important to display the contents of the other_tag in the execution. QUESTION 20 Which two types of SQL statements will benefit from dynamic sampling? A. SQL statements that are executed parallel B. SQL statement that use a complex predicate expression when extended statistics are not available. C. SQL statements that are resource-intensive and have the current statistics D. SQL statements with highly selective filters on column that has missing index statistics E. Short-running SQL statements Correct Answer: BD

22 /Reference: B:Onescenario where DS is used is when the statement contains a complex predicate expression and extended statistics are not available. Extended statistics were introduced in Oracle Database 11g Release 1 with the goal to help the optimizer get good quality cardinality estimates for complex predicate expressions. D: DSIt is typically used to compensate for missing or insufficient statistics that would otherwise lead to a very bad plan. Note: *Dynamic sampling (DS) was introduced in Oracle Database 9i Release 2 to improve the optimizer's ability to generate good execution plans. *During the compilation of a SQL statement, the optimizer decides whether to use DS or not by considering whether the available statistics are sufficient to generate a good execution plan. If the available statistics are not enough, dynamic sampling will be used. It is typically used to compensate for missing or insufficient statistics that would otherwise lead to a very bad plan. It is typically used to compensate for missing or insufficient statistics that would otherwise lead to a very bad plan. For the case where one or more of the tables in the query does not have statistics, DS is used by the optimizer to gather basic statistics on these tables before optimizing the statement. The statistics gathered in this case are not as high a quality or as complete as thestatistics gathered using the DBMS_STATS package. This trade off is made to limit the impact on the compile time of the statement. QUESTION 21 You are administering a database supporting an OLTP workload. A new module was added to one of the applications recently in which you notice that the SQL statements are highly resource intensive in terms of CPU, I/O and temporary space. You created a SQL Tuning Set (STS) containing all resource-intensive SQL statements. You want to analyze the entire workload captured in the STS. You plan to run the STS through the SQL Advisor. Which two recommendations can you get? A. Combing similar indexes into a single index B. Implementing SQL profiles for the statements C. Syntactic and semantic restructuring of SQL statements D. Dropping unused or invalid index. E. Creating invisible indexes for the workload F. Creating composite indexes for the workload Correct Answer: CF /Reference: The output of the SQL Tuning Advisor is in the form of an advice or recommendations, along with a rationale for each recommendation and its expected benefit. The recommendation relates to collection of statistics on objects, creation of new indexes(f), restructuring of the SQL statement(c), or creation of a SQL profile. You can choose to accept the recommendation to complete the tuning of the SQL statements. Reference: OracleDatabase Performance Tuning Guide11g,SQL Tuning Advisor QUESTION 22 A new application module is deployed on middle tier and is connecting to your database. You want to monitor the performance of the SQL statements generated from the application.

23 To accomplish this, identify the required steps in the correct order from the steps given below: 1. Use DBNMS_APPLICATION_INFO to set the name of the module 2. Use DBMS_MONITOR.SERV_MOD_ACT_STAT_ENABLE to enable statistics gathering for the module. 3. Use DBMS_MONITOR.SERV_MOD_ACT_TRACE_ENABLE to enable tracing for the service 4. Use the trcsess utility to consolidate the trace files generated. 5. Use the tkprof utility to convert the trace files into formatted output. A. 1, 2, 3, 4, 5 B. 2, 3, 1, 4, 5 C. 3, 1, 2, 4, 5 D. 1, 2, 4, 5 E. 1, 3, 4, 5 F. 2, 1, 4, 5 Correct Answer: A /Reference: Note: *Before tracing can be enabled, the environment must first be configuredto enable gathering of statistics. * (gather statistics):dbms_monitor.serv_mod_act_stat_enable Enables statistic gathering for a given combination of Service Name, MODULE and ACTION *DBMS_MONITOR.SERV_MOD_ACT_TRACE_ENABLE Enables SQL tracing for a given combination of Service Name, MODULE and ACTION globally unless an instance_name is specified. dbms_monitor.serv_mod_act_trace_enable( service_name IN VARCHAR2, module_name IN VARCHAR2 DEFAULT ANY_MODULE, action_name IN VARCHAR2 DEFAULT ANY_ACTION, waits IN BOOLEAN DEFAULT TRUE, binds IN BOOLEAN DEFAULT FALSE, instance_name IN VARCHAR2 DEFAULT NULL, plan_stat IN VARCHAR2 DEFAULT NULL); SELECT instance_name FROM gv$instance; exec dbms_monitor.serv_mod_act_trace_enable('testserv', dbms_monitor.all_modules, dbms_monitor.all_actions, TRUE, TRUE, 'orabase'); exec dbms_monitor.serv_mod_act_trace_disable('testserv', dbms_monitor.all_modules, dbms_monitor.all_actions, 'orabase'); *When solving tuning problems, session traces are very useful and offer vital information. Traces are simple and straightforward for dedicated server sessions, but for shared server sessions, many processes are involved. The trace pertaining to the user session is scattered across different trace files belonging to different processes. This makes it difficult to get a complete picture of the

24 life cycle of a session. Now there is a new tool, a command line utility called trcsess to help read the trace files. The trcsess command-line utility consolidates trace information from selected trace files, based on specified criteria. The criteria include session id, client id, service name, action name and module name. *Once the trace files have been consolidated (with trcsess), tkprof can be run against the consolidated trace file for reporting purposes. QUESTION 23 One of your databases supports a mixed workload. When monitoring SQL performance, you detect many direct paths reads full table scans. What are the two possible causes? A. Histograms statistics not available B. Highly selective filter on indexed columns C. Too many sort operations performed by queries D. Indexes not built on filter columns E. Too many similar type of queries getting executed with cursor sharing disabled Correct Answer: BD /Reference: Note: *The direct path read Oracle metric occurs during Direct Path operations when the data is asynchronously read from the database files into the PGA instead of into the SGA data buffer. Direct reads occur under these conditions: - When reading from the TEMP tablespace (a sort operation) - When reading a parallel full-table scan (parallel query factotum (slave) processes) - Reading a LOB segment *The optimizer uses a full table scan in any of the following cases: - Lack of Index - Large Amount of Data - Small Table - High Degree of Parallelism QUESTION 24 Examine the Exhibit. Which two options are true about the execution plan and the set of statements? Exhibit:

25 A. The query uses a partial partition-wise join. B. The degree of parallelism is limited to the number of partitions in the EMP_RANGE_DID table. C. The DEPT table id dynamically distributed based on the partition keys of the EMP_RANGE_DID table. D. The server process serially scans the entire DEPT table for each range partition onthe

26 EMP_RANGE_DID table. E. The query uses a full partition-wise join. Correct Answer: CE /Reference: Note the "px partition range all" in the execution plan. Note: *PX PARTITION RANGE (ALL) Description Parallel execution - iterate over all range partitioned table *Full partition-wise joins can occur if two tables that are co-partitioned on the same key are joined in a query. The tables can be co-partitioned at the partition level, or at the subpartition level, or at a combination of partition and subpartition levels. Reference partitioning is an easy way to guarantee co-partitioning. Full partition-wise joins can be executed serially and in parallel. *Oracle Database can perform partial partition-wise joins only in parallel. Unlike full partition-wise joins, partial partition-wise joins require you to partition only one table on the join key, not both tables. The partitioned table is referred to as the reference table. The other table may or may not be partitioned. Partial partition-wise joins are more common than full partition-wise joins. To execute a partial partition-wise join, the database dynamically partitions or repartitions the other table based on the partitioning of the reference table. After the other table is repartitioned, the execution is similar to a full partition-wise join. QUESTION 25 What are three common reasons for SQL statements to perform poorly? A. Full table scans for queries with highly selective filters B. Stale or missing optimizer statistics C. Histograms not existing on columns with evenly distributed data D. High index clustering factor E. OPTIMIZER_MODE parameter set to ALL_ROWS for DSS workload Correct Answer: ABD /Reference: D:The clustering_factor measures how synchronized an index is with the data in a table. A table with a high clustering factor is out-of-sequence with the rows and large index range scans will consume lots of I/O. Conversely, an index with a low clustering_factor is closely aligned with the table and related rows reside together of each data block, making indexes very desirable for optimal access. Note: * (Not C)Histograms are feature in CBO and it helps to optimizer to determine how data are skewed(distributed) with in the column. Histogram is good to create for the column which are included in the WHERE clause where the column is highly skewed. Histogram helps to optimizer to decide whether to use an index or full-table scan or help the optimizer determine the fastest table join order. *OPTIMIZER_MODE establishes the default behavior for choosing an optimization approach for the instance.

27 all_rows The optimizer uses a cost-based approach for all SQL statements in the session and optimizes with a goal of best throughput (minimum resource use to complete the entire statement). QUESTION 26 Examine the utilization parameters for an instance: You notice that despite having an index on the column used in the where clause, queries use full table scans with highly selective filters. What are two possible reasons for the optimizer to use full table scans instead of index unique scans and index range scans? A. The OPTIMIZER_MODE parameter is set to ALL_ROWS. B. The clustering factor for the indexes is high. C. The number of leaf blocks for the indexes is high. D. The OPTIMIZER_INDEX_COST_ADJ initialization parameter is set to 100. E. The blocks fetched by the query are greater than the value specified by the DB_FILE_MULTIBLOCK_READ_COUNT parameter. Correct Answer: DE /Reference: D:OPTIMIZER_INDEX_COST_ADJ lets you tune optimizer behavior for access path selection to be more or less index friendly that is, to make the optimizer more or less prone to selecting an index access path over a full table scan. The default for this parameter is 100 percent, at which the optimizer evaluates index access paths at the regular cost. Any other value makes the optimizer evaluate the access path at that percentage of the regular cost. For example, a setting of 50 makes the index access path look half as expensive as normal. E:DB_FILE_MULTIBLOCK_READ_COUNT is one of the parameters you can use to minimize I/O during table scans. It specifies the maximum number of blocks read in one I/O operation during a sequential scan. The total number of I/Os needed to perform a full table scan depends on such factors as the size of the table, the multiblock read count, and whether parallel execution is being utilized for the operation. As of Oracle Database 10g release 2, the default value of this parameter is a value that corresponds to the maximum I/O size that can be performed efficiently. This value is platformdependent and is 1MB for most platforms.because the parameter is expressed in blocks, it will be set to a value that is equal to the maximum I/O size that can be performed efficiently divided by the standard block size. Note that if the number of sessions is extremely large the multiblock read count value is decreased to avoid the buffer cache getting flooded with too many table scan buffers.

28 Even though the default value may be a large value, the optimizer will not favor large plans if you do not set this parameter. It would do so only if you explicitly set this parameter to a large value. Online transaction processing (OLTP) and batch environments typically have values in the range of 4 to 16 for this parameter. DSS and data warehouse environments tend to benefit most from maximizing the value of this parameter. The optimizer is more likely to choose a full table scan over an index if the value of this parameter is high. Note: *OPTIMIZER_MODE establishes the default behavior for choosing an optimization approach for the instance. Values: first_rows_n The optimizer uses a cost-based approach and optimizes with a goal of best response time to return the first n rows (where n = 1, 10, 100, 1000). first_rows The optimizer uses a mix of costs and heuristics to find a best plan for fast delivery of the first few rows. all_rows The optimizer uses a cost-based approach for all SQL statements in the session and optimizes with a goal of best throughput (minimum resource use to complete the entire statement). QUESTION 27 Tracing has been enabled for the HR user. You execute the following command to check the contents of the orcl_25052.trc trace file, which was generated during tracing: Which two statements are correct about the execution of the command? A. SCRIPT.SQL stores the statistics for all traced SWL statements. B. Execution plans for SQL statements are stored in TEMP_PLAN_TABLE and can be queried by the user. C. SQL statements in the output files are stored in the order of elapsed time. D. TKPROF usetemp_plan_table in the HR schema as a temporary plan table. E. Recursive SQL statements are included in the output file. Correct Answer: CD /Reference: QUESTION 28 You are administering a database that supports an OLTP application. To set statistics preferences, you issued the following command:

29 SQL > DBMS_STATS.SET_GLOBAL_PREFS ( ESTIMATE_PERCENT, 9 ); What will be the effect of executing this procedure? A. It will influence the gathering of statistics for a table based on the value specified for ESTIMATE_PERCENT provided on table preferences for the same table exist. B. It will influence dynamic sampling for a query to estimate the statistics based on ESTIMATE_PERCENT. C. The automatic statistics gathering job running in the maintenance window will use global preferences even if table preferences for the same table exist. D. New objects created will use global preference even if table preferences are specified. Correct Answer: C /Reference: Note: *With the DBMS_STATS package you can view and modify optimizer statistics gathered for database objects. * TheSET_GLOBAL_PREFSproceduree is used to set the global statistics preferences. *ESTIMATE_PERCENT - The value determines the percentage of rows to estimate. The valid range is [ ,100]. Use the constant DBMS_STATS.AUTO_SAMPLE_SIZE to have Oracle determine the appropriate sample size for good statistics. This is the default. QUESTION 29 Examine the parallelism parameter for your instance: Now examine the Consumer Group resource plan containing parallel statement directives:

30 Which two are true about parallel statement queuing when this plan is active? A. Urgent_group sessions collectively can consume up to 64 parallel execution servers before queuing starts for this consumer group. B. ETL_GROUP sessions can collectively consume up to 64 parallel execution servers before the queuing starts for this consumer. C. A single OTHER_GROUPS session will execute serially once it is queued for six minutes. D. A single ETL_GROUP session can consume up to eight parallel execution servers. E. A single ETL_GROUP session can consume up to 32 parallel execution servers. F. A single OTHER_GROUPS session will execute in parallel once it is queued for six minutes. Correct Answer: CD /Reference: *PARALLEL_SERVERS_TARGET specifies the number of parallel server processes allowed to run parallel statements before statement queuing will be used. When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle will queue SQL statements that require parallel execution, if the necessary parallel server processes are not available. Statement queuing will begin once the number of parallel server processes active on the system is equal to or greater than PARALLEL_SERVER_TARGET. By default, PARALLEL_SERVER_TARGET is set lower than the maximum number of parallel server processes allowed on the system (PARALLEL_MAX_SERVERS) to ensure each parallel statement will get all of the parallel server resources required and to prevent overloading the system with parallel server processes. * PARALLEL_QUIT_TIMEOUT * PARALLEL_DEGREE_LIMIT With automatic degree of parallelism, Oracle automatically decides whether or not a statement should execute in parallel and what degree of parallelism the statement should use. The optimizer automatically determines the degree of parallelism for a statement based on the resource

31 requirements of the statement. However, the optimizer will limit the degree of parallelism used to ensure parallel server processes do not flood the system. This limit is enforced by PARALLEL_DEGREE_LIMIT. Values: The maximum degree of parallelism is limited by the number of CPUs in the system. The formula used to calculate the limit isparallel_threads_per_cpu * CPU_COUNT * the number of instances available (by default, all the opened instances on the cluster but can be constrained using PARALLEL_INSTANCE_GROUP or service specification). This is the default. The maximum degree of parallism the optimizer can use is limited by the I/O capacity of the system. The value is calculated by dividing the total system throughput by the maximum I/O bandwidth per process. You must run the DBMS_RESOURCE_MANAGER.CALIBRATE_IO procedure on the system in order to use the IO setting. This procedure will calculate the total system throughput and the maximum I/O bandwidth per process. integer A numeric value for this parameter specifies the maximum degree of parallelism the optimizer can choose for a SQL statement when automatic degree of parallelism is active. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO orlimited. QUESTION 30 View the Exhibit1 and examine the structure and indexes for the MYSALES table. The application uses the MYSALES table to insert sales record. But this table is also extensively used for generating sales reports. The PROD_ID and CUST_ID columns are frequently used in the WHERE clause of the queries. These columns are frequently used in WHERE clause of the queries. These columns have few distinct values relative to the total number of rows in the table. View exhibit 2 and examine one of the queries and its auto trace output. What should you do to improve the performance of the query? 30_1 (exhibit): 30_2 (exhibit):

32

33 A. Use the INDEX_COMBINE hint in the query. B. Create composite index involving the CUST_ID and PROD_ID columns. C. Gather histograms statistics for the CUST_ID and PROD_ID columns. D. Gather index statistics for the MYSALES_PRODID_IDX and MYSALES_CUSTID_IDX indexes. Correct Answer: D /Reference: Note: *Statistics quantify the data distribution and storage characteristics of tables, columns, indexes,and partitions. *INDEX_COMBINE Forces a bitmap index access path on tab. Primarily this hint just tells Oracle to use the bitmap indexes on table tab. Otherwise Oracle will choose the best combination of indexes it can think of based on the statistics. If it is ignoring a bitmap index that you think would be helpful, you may specify that index plus all of the others taht you want to be used. Note that this does not force the use of those indexes, Oracle will still make cost based choices. *Histograms Opportunities Any column used in a where clause with skewed data Histograms are NOT just for indexed columns. Adding a histogram to an un-indexed column that is used in QUESTION 31 You are administering database that supports an OLTP workloads. Most of the queries use an index range scan or index unique scan as access methods. Which three scenarios can prevent the index access being used by the queries? A. When highly selective filters is applied on an indexed column of a table with sparsely populated blocks. B. When the rows are filtered with an IS NULL operator on the column with a unique key defined C. When the histogram statistics are not collected for the columns used in where clause. D. When a highly selective filter is applied on the indexed column and the index has very low value for clustering factor. E. When the statistics for the table are not current. Correct Answer: BDE /Reference: D:The clustering_factor measures how synchronized an index is with the data in a table. A table with a high clustering factor is out-of-sequence with the rows and large index range scans will consume lots of I/O. Conversely, an index with a low clustering_factor is closely aligned with the table and related rows reside together of each data block, making indexes very desirable for optimal access. Note: *Oracle SQL not using an index is a common complaint, and it s often because the optimizer thinks that a full-scan is cheaper than index access. Oracle not using an index can be due to: *(E)Bad/incomplete statistics Make sure to re-analyze the table and index with dbms_stats to ensure that the optimizer has good metadata. *Wrong optimizer_mode The first_rows optimizer mode is to minimize response time, and it is more likely to use an index than the default all_rows mode.

34 *Bugs See these important notes on optimizer changes in 10g that cause Oracle not to use an index. *Cost adjustment In some cases, the optimizer will still not use an index, and you must decrease optimizer_index_cost_adj. QUESTION 32 You are logged in as the HR user and you execute the following procedure: SQL > exec DBMS_STATS.SET_TABLE_PREFS ( HR, EMPLOYEES, PUBLISH, FALSE ); SQL> exec DBMS_STATS.GATHER_TABLE_STATS ( HR, EMPLOYEES ); Which statement is true about the newly gathered statistics? A. They are temporary and purged when the session exits. B. They are used by the optimizer for all sessions. C. They are locked and cannot be overwritten. D. They are marked as pending and stored in the pending statistics table. Correct Answer: D /Reference: In previous database versions, new optimizer statistics were automatically published when they were gathered. In 11g this is still the default action, but you now have the option of keeping the newly gathered statistics in a pending state until you choose to publish them. The DBMS_STATS.GET_PREFS function allows you to check the 'PUBLISH' attribute to see if statistics are automatically published. The default value of TRUE means they are automatically published, while FALSE indicates they are held in a pending state. Reference:Statistics Collection Enhancements in Oracle Database 11g Release 1,Pending Statistics QUESTION 33 You enable auto degree of parallelism (DOP) for your database instance. Examine the following query: Which two are true about the execution of statement? A. Dictionary DOP for the objects accessed by the query is used to determine the statement DOP. B. Auto DOP is used to determine the statement DOP only if the estimated serial execution time exceeds PARALLEL_MIN_TIME_THRESHOLD. C. Dictionary DOP is used to determine the statement DOP only if the estimated serial execution

35 time exceeds PARALLEL_MIN_TIME_THRESHOLD. D. The statement will be queued if insufficient parallel execution slaves are available to satisfy the statements DOP. E. The statement will be queued if the number of busy parallel execution servers exceeds PARALLEL_SERVERS_TARGET. F. The statements may execute serially. Correct Answer: BF /Reference: Not B, not D:MANUAL - This is the default. Disables Auto DOP, statement queuing and in-memory parallel execution. It reverts the behavior of parallel execution to what it was previous to Oracle Database 11g, Release 2 (11.2). C:PARALLEL_MIN_TIME_THRESHOLD specifies the minimum execution time a statement should have before the statement is considered for automatic degree of parallelism. By default, this is set to 30 seconds. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. Note: *PARELLEL (MANUAL) You can use the PARALLEL hint to force parallelism. It takes an optional parameter: the DOP at which the statement should run. The following example forces the statement to use Oracle Database 11g Release 1 (11.1) behavior: SELECT /*+ parallel(manual) */ ename, dname FROM emp e, dept d WHERE e.deptno=d.deptno; *PARALLEL_SERVERS_TARGET specifies the number of parallel server processes allowed to run parallel statements before statement queuing will be used. When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle will queue SQL statements that require parallel execution, if the necessary parallel server processes are not available. Statement queuing will begin once the number of parallel server processes active on the system is equal to or greater than PARALLEL_SERVER_TARGET. By default, PARALLEL_SERVER_TARGET is set lower than the maximum number of parallel server processes allowed on the system (PARALLEL_MAX_SERVERS) to ensure each parallel statement will get all of the parallel server resources required and to prevent overloading the system with parallel server processes. Note that all serial (non-parallel) statements will execute immediately even if statement queuing has been activated. QUESTION 34 Examine the exhibit.

36 Which is true based on the information obtainable from the execution plan? Exhibit: A. A full partition-wise join performed between the EMPLOYEES and DEPARTMENTS tables. B. A full table scan on the DEPARTMENTS table performed serially by the query coordinator. C. A full table scan on the DEPARTMENTS table is performed serially by a single parallel execution server process. D. A partial partition-wise join performed between the EMPLOYEES and DEPARTMENTS tables. E. A full table scan on the EMPLOYEES table is done in parallel. Correct Answer: E /Reference: PX BLOCK ITERATORThis operation is typically the first step in a parallel pipeline. The BLOCK ITERATOR breaks up the table into chunks that are processed by each of the parallel servers involved. Incorrect: B, C: The scan on the Departsments table is done in parallel. Note: *As per exhibit: Line 7 is run first, followed by line 6. * Example with same structure of execution plan:

37 Here s how to read the plan:1. The first thing done is at line 9 an index fast full scan on SYS.OBJ$.I_OBJ1 index. This is done in parallel, as indicated from the PX SEND line above.2. In line 8, we re doing a PX SEND BROADCAST operation. When joining tables in parallel, Oracle can choose to either broadcast results (rows) from one operation to apply to the other table scan, or it can choose PX SEND HASH. In this case, our CBO determined that a BROADCOAST was appropriate because the results from the OBJ$ table were much lower than the MYOBJ table3. Line 7, the PX RECEIVE step, is basically the consumer of the broadcasted rows in step 84. Line 6 is an in-memory BUFFER SORT of the rows returned from the index scan on OBJ$5. Lines 11 and 10, respectively, indicate the full scan and PX BOCK ITERATOR operation for the granules involved in the 8 PQ servers6. In line 5, Oracle is doing a hash join on the resulting rows from the parallel scans on MYOBJ and OBJ$7. Line 4 is a per-pq server sort of data from the joind PQ servers8. Line 3 is the consumer QC that holds the result of the each of the PQ servers9. Line 2 is the PX Coordinator (QC) collecting, or consuming the rows of the joined data10. Line 1 is the final SORT AGGREGATE line that performs the grouping function QUESTION 35 Examine the exhibit to view the query and its execution plan? What two statements are true?

38 Exhibit:

39

40 A. The HASH GROUP BY operation is the consumer of the HASH operation. B. The HASH operation is the consumer of the HASH GROUP BY operation. C. The HASH GROUP BY operation is the consumer of the TABLE ACCESS FULL operation for the CUSTOMER table. D. The HASH GROUP BY operation is consumer of the TABLE ACCESS FULL operation for the SALES table. E. The SALES table scan is a producer for the HASH JOIN operation. Correct Answer: AE /Reference: A, not C, not D: Line 3, HASH GROUP BY, consumes line 6 (HASH JOIN BUFFERED). E: Line 14, TABLE ACCESS FULL (Sales), is one of the two producers for line 6 (HASH JOIN). QUESTION 36 A database supports three applications: CRM, ERP, and ACC. These applications connect to the database by using three different services: CRM_SRV for the CRM application, ERP_SRV for the ERP application, and ACC_SRV for the ACC application. You enable tracing for the ACC_SRV service by issuing the following command: SQL> EXECUTE DBMS for the ACC_SRV service by issuing the following command: SQL> EXECUITIVE DBMS_MONITOR. SERV_MOD_ACT_TRACE_ENABLE (service_name => ACC_SRV, waits => TRUE, binds = > FALSE, instance_name = > inst1 ); Which statement is true? A. All trace information for the service connection to inst1 will be stored in a single trace file. B. A trace file is not created because the module name is not specified. C. A single trace file is created for each session that uses the ACC_SRV service. D. Only those SQL statements that are identified with the ACC_SRV service executed on the inst1 instance are recorded in trace files. E. All trace information for the ACC_SRV service connected to inst1 is stored in multiple trace files, which can be consolidated by using the tkprof utility. Correct Answer: C /Reference: SERV_MOD_ACT_TRACE_ENABLE serv_mod_act_trace_enable and serv_mod_act_trace_disable, which enables and disables trace for given service_name, module and action. For example for a given service name you can trace all session started from SQL*Plus. Module and action in your own created application can be set using dbms_application_info set_module and set_action procedures. serv_mod_act_trace_enable fills sys table wri$_tracing_enabled and view dba_enabled_traces on top of this table as follows: SQL> exec dbms_monitor.serv_mod_act_trace_enable(service_name=>'orcl', module_name=>'sql*plus')

41 PL/SQL procedure successfully completed. SQL> select * from sys.wri$_tracing_enabled; TRACE_TYPE PRIMARY_ID QUALIFIER_ID1 QUALIFIER_ID2 INSTANCE_NAME FLAGS orcl SQL*Plus 8 SQL> select * from dba_enabled_traces; TRACE_TYPE PRIMARY_ID QUALIFIER_ID1 QUALIFIER_ID2 WAITS BINDS INSTANCE_NAME SERVICE_MODULE orcl SQL*Plus TRUE FALSE QUESTION 37 Examine the following anonymous PL/SQL code block of code: Which two are true concerning the use of this code? A. The user executing the anonymous PL/SQL code must have the CREATE JOB system privilege. B. ALTER SESSION ENABLE PARALLEL DML must be executed in the session prior to executing the anonymous PL/SQL code. C. All chunks are committed together once all tasks updating all chunks are finished. D. The user executing the anonymous PL/SQL code requires execute privilege on the DBMS_JOB package. E. The user executing the anonymous PL/SQL code requires privilege on the DBMS_SCHEDULER package. F. Each chunk will be committed independently as soon as the task updating that chunk is

42 finished. Correct Answer: AE /Reference: A(not D, not E): To use DBMS_PARALLEL_EXECUTE to run tasks in parallel, your schema will need the CREATE JOB system privilege. E (not C):DBMS_PARALLEL_EXECUTE now provides the ability to break up a large table according to a variety of criteria, from ROWID ranges to key values and user-defined methods. You can then run a SQL statement or a PL/SQL block against these different chunks of the table in parallel, using the database scheduler to manage the processes running in the background. Error logging, automatic retries, and commits are integrated into the processing of these chunks. Note: *The DBMS_PARALLEL_EXECUTE package allows a workload associated with a base table to be broken down into smaller chunks which can be run in parallel. This process involves several distinct stages. 1.Create a task 2.Split the workload into chunks CREATE_CHUNKS_BY_ROWID CREATE_CHUNKS_BY_NUMBER_COL CREATE_CHUNKS_BY_SQL 3.Run the task RUN_TASK User-defined framework Task control 4.Check the task status 5.Drop the task *The workload is associated with a base table, which can be split into subsets or chunks of rows. There are three methods of splitting the workload into chunks. CREATE_CHUNKS_BY_ROWID CREATE_CHUNKS_BY_NUMBER_COL CREATE_CHUNKS_BY_SQL The chunks associated with a task can be dropped using the DROP_CHUNKS procedure. *CREATE_CHUNKS_BY_ROWID The CREATE_CHUNKS_BY_ROWID procedure splits the data by rowid into chunks specified by the CHUNK_SIZE parameter. If the BY_ROW parameter is set to TRUE, the CHUNK_SIZE refers to the number of rows, otherwise it refers to the number of blocks. Reference:TECHNOLOGY: PL/SQL Practices,On Working in Parallel QUESTION 38 Examine the following query and execution plan:

43 Which query transformation technique is used in this scenario? A. Join predicate push-down B. Subquery factoring C. Subquery unnesting

44 D. Join conversion Correct Answer: A /Reference: *Normally, a view cannot be joined with an index-based nested loop (i.e., index access) join, since a view, in contrast with a base table, does not have an index defined on it. A view can only be joined with other tables using three methods: hash, nested loop, and sort-merge joins. *The following shows the types of views on which join predicate pushdown is currently supported. UNION ALL/UNION view Outer-joined view Anti-joined view Semi-joined view DISTINCT view GROUP-BY view QUESTION 39 You enabled auto degree of parallelism (DOP) for your instance. Examine the query: Which two are true about the execution of this query? A. Dictionary DOP will be used, ifpresent, on the tables referred in the query. B. DOP is calculated if the calculated DOP is 1. C. DOP is calculated automatically. D. Calculated DOP will always by 2 or more. E. The statement will execute with auto DOP only when PARALLEL_DEGREE_POLICY is set to AUTO. Correct Answer: CD /Reference: C:*You can use the PARALLEL hint to force parallelism. It takes an optional parameter: the DOP at which the statement should run. In addition, theno_parallel hint overrides a PARALLEL parameter in the DDL that created or altered the table. The following example illustrates computing the DOP the statement should use: SELECT /*+ parallel(auto) */ ename, dname FROM emp e, dept d WHERE e.deptno=d.deptno; Not A: to override the dictionary dop,we could use hints at object level

45 Not E: statement hints overridetheparallel_degree_policy. Note: *Automatic Parallel Degree Policy When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle Database automatically decides if a statement should execute in parallel or not and what DOP it should use. Oracle Database also determines if the statement can be executed immediately or if it is queued until more system resources are available. Finally, Oracle Database decides if the statement can take advantage of the aggregated cluster memory or not. The following is a summary of parallel statement processing when parallel degree policy is set to automatic. QUESTION 40 View Exhibit1 and examine the structure and indexes for the MYSALES table. The application uses the MYSALES table to insert sales record. But this table is also extensively used for generating sales reports. The PROD_ID and CUST_ID columns are frequently used in the WHERE clause of the queries. These columns have few distinct values relative to the total number of rows in the table. The MYSALES table has 4.5 million rows. View exhibit 2 and examine one of the queries and its autotrace output. Which two methods can examine one of the queries and its autotrace output? 40_1 (exhibit): 40_2 (exhibit):

46 A. Drop the current standard balanced B* Tree indexes on the CUST_ID and PROD_ID columns and re-create as bitmapped indexes. B. Use the INDEX_COMBINE hint in the query.

47 C. Create a composite index involving the CUST_ID and PROD_ID columns. D. Rebuild the index to rearrange the index blocks to have more rows per block by decreasing the value for PCTFRE attribute. E. Collect histogram statistics for the CUST_ID and PROD_ID columns. Correct Answer: BC /Reference: B:The INDEX hint explicitly chooses an index scan for the specified table. You can use the INDEX hint for domain, B-tree, bitmap, and bitmap join indexes. However, Oracle recommends using INDEX_COMBINE rather than INDEX for the combination of multiple indexes, because it is a more versatile hint. C: Combiningthe CUST_ID and PROD_IDcolumns into an composite index would improve performance. QUESTION 41 Examine the Exhibit to view the structure of an indexes for the SALES table. The SALES table has rows. The CUST_ID column has 2079 distinct values. What would you do to influence the optimizer for better selectivity? Exhibit:

48

49 A. Drop bitmap index and create balanced B*Tree index on the CUST_ID column. B. Create a height-balanced histogram for the CUST_ID column. C. Gather statistics for the indexes on the SALES table. D. Use the ALL_ROWS hint in the query. Correct Answer: D /Reference: OPTIMIZER_MODE establishes the default behavior for choosing an optimization approach for the instance. Values: FIRST_ROWS_N - The optimizer uses a cost-based approach and optimizes with a goal of best response time to return the first n rows (where n = 1, 10, 100, 1000). FIRST_ROWS - The optimizer uses a mix of costs and heuristics to find a best plan for fast delivery of the first few rows. ALL_ROWS - The optimizer uses a cost-based approach for all SQL statements in the session and optimizes with a goal of best throughput (minimum resource use to complete the entire statement). QUESTION 42 Which three are tasks performed in the hard parse stage of a SQL statement executions? A. Semantics of the SQL statement are checked. B. The library cache is checked to find whether an existing statement has the same hash value. C. The syntax of the SQL statement is checked. D. Information about location, size, and data type is defined, which is required to store fetched values in variables. E. Locks are acquired on the required objects. Correct Answer: BDE /Reference: Parse operations fall into the following categories, depending on the type of statement submitted and the result of the hash check: A)Hard parse If Oracle Database cannot reuse existing code, then it must build a new executable version of the application code. This operation is known as a hard parse, or a library cache miss. The database always perform a hard parse of DDL. During the hard parse, the database accesses the library cache and data dictionary cache numerous times to check the data dictionary. When the database accesses these areas, it uses a serialization device called a latch on required objects so that their definition does not change (see "Latches"). Latch contention increases statement execution time and decreases concurrency. B)Soft parse A soft parse is any parse that is not a hard parse. If the submitted statement is the same as a reusable SQL statement in the shared pool, then Oracle Database reuses the existing code. This reuse of code is also called a library cache hit. Soft parses can vary in the amount of work they perform. For example, configuring the session cursor cache can sometimes reduce the amount of latching in the soft parses, making them "softer."

50 In general, a soft parse is preferable to a hard parse because the database skips the optimization and row source generation steps, proceeding straight to execution. Incorrect: A, C:During the parse call, the database performs the following checks: Syntax Check Semantic Check Shared Pool Check The hard parse is within Shared Pool check. Reference:Oracle Database Concepts11g,SQL Parsing QUESTION 43 You are administering a database supporting an OLTP application. The application runs a series of extremely similar queries the MYSALES table where the value of CUST_ID changes. Examine Exhibit1 to view the query and its execution plan. Examine Exhibit 2 to view the structure and indexes for the MYSALES table. The MYSALES table has 4 million records. Data in the CUST_ID column is highly skewed. Examine the parameters set for the instance: Which action would you like to make the query use the best plan for the selectivity? 43_1 (exhibit):

51 43_2 (exhibit):

52 A. Decrease the value of the OPTIMIZER_DYNAMIC_SAMPLING parameter to 0. B. Use the /*+ INDEX(CUST_ID_IDX) */ hint in the query. C. Drop the existing B* -tree index and re-create it as a bitmapped index on the CUST_ID column. D. Collect histogram statistics for the CUST_ID column and use a bind variable instead of literal values. Correct Answer: D /Reference: Using Histograms In some cases, the distribution of values within a column of a table will affect the optimizer's decision to use an index vs. perform a full-table scan. This scenario occurs when the value with a where clause has a disproportional amount of values, making a full-table scan cheaper than index access. A column histogram should only be created when we have data skew exists or is suspected. QUESTION 44 Which two are the fastest methods for fetching a single row from a table based on an equality predicate? A. Fast full index scan on an index created for a column with unique key B. Index unique scan on an created for a column with unique key C. Row fetch from a single table hash cluster D. Index range scan on an index created from a column with primary key

53 E. Row fetch from a table using rowid Correct Answer: CE /Reference: A scan is slower than a row fetch (from hash value or rowid). QUESTION 45 An application user complains about statement execution taking longer than usual. You find that the query uses a bind variable in the WHERE clause as follows: You want to view the execution plan of the query that takes into account the value in the bind variable PCAT. Which two methods can you use to view the required execution plan? A. Use the DBMS_XPLAN.DISPLAY function to view the execution plan. B. Identify the SQL_ID for the statementsand use DBMS_XPLAN.DISPLAY_CURSOR for that SQL_ID to view the execution plan. C. Identify the SQL_ID for the statement and fetch the execution plan PLAN_TABLE. D. View the execution plan for the statement fromv$sql_plan. E. Execute the statement with different bind values and set AUTOTRACE enabled for session. Correct Answer: BD /Reference: D:V$SQL_PLAN contains the execution plan information for each child cursor loaded in the library cache. B:The DBMS_XPLAN package supplies five table functions: DISPLAY_SQL_PLAN_BASELINE - to display one or more execution plans for the SQL statement identified by SQL handle DISPLAY - to format and display the contents of a plan table. DISPLAY_AWR - to format and display the contents of the execution plan of a stored SQL statement in the AWR. DISPLAY_CURSOR - to format and display the contents of the execution plan of any loaded cursor. DISPLAY_SQLSET - to format and display the contents of the execution plan of statements stored in a SQL tuning set. QUESTION 46 Which statement is true about an SQL plan baselines that are fixed?

54 A. New plans are added automatically by the optimizer to the baseline and are automatically evolved. B. New, better plans are added automatically as a fixed plan baseline. C. New plan can be manually loaded to the baseline from the cursor cache or a SQL tuning set. D. New plans can be added as fixed plans to the baseline by using the SQL Tuning Advisor to generate a SQL profile and by accepting the SQL profile. Correct Answer: D /Reference: When a SQL statement with a fixed SQL plan baseline is tuned using the SQL Tuning Advisor, a SQL profile recommendation has special meaning. When the SQL profile is accepted, the tuned plan is added to the fixed SQL plan baseline as a non-fixed plan. However, as described above, the optimizer will not use the tuned plan as long as a reproducible fixed plan is present.therefore, the benefit of SQL tuning may not be realized. To enable the use of the tuned plan, manually alter the tuned plan to a fixed plan by setting its FIXED attribute to YES. Note: It is also possible to influence the optimizer s choice of plan when it is selecting a plan from a SQL plan baseline. SQL plan baselines can be marked as fixed. Fixed SQL plan baselines indicate to the optimizer that they are preferred. If the optimizer is costing SQL plan baselines and one of the plans is fixed, the optimizer will only cost the fixed plan and go with that if it is reproducible. If the fixed plan(s) are not reproducible the optimizer will go back and cost the remaining SQL plan baselines and select the one with the lowest cost. Note that costing a plan is nowhere near as expensive as a hard parse. The optimizer is not looking at all possible access methods but at one specific access path. Reference: OracleDatabase Performance Tuning Guide11g,Using Fixed SQL Plan Baselines Reference:SQL Plan Management in Oracle Database 11g QUESTION 47 Examine the initializing parameters: An index exists on the column used in the WHERE of a query. You execute the query for the first time today and notice that the query is not using the index. The CUSTOMERS table has rows. View the exhibit and examine the query and its execution plan. What can be the two reasons for full table scan? Exhibit:

55 A. The value of the OPTIMIZER_INDEX_COST_ADJ parameter is set to a low value. B. The blocks fetched by the query are greater than the value specified by the DB_FILE_MULTIBLOCK_READ_COUNT parameter. C. The statistics for the CUSTOMERS table and the indexes stale. D. The OPTIMIZER_MODE parameter is set to ALL_ROWS. E. Histogram statistics for CUST_CITY_ID are missing. F. Average number of rows per block for the CUSTOMERS table is low. Correct Answer: CD /Reference: C: Old statistics could cause this problem. D:Histograms are feature in CBO and it helps to optimizer to determine how data are skewed(distributed) with in the column. Histogram is good to create for the column which are included in the WHERE clause where the column is highly skewed. Histogram helps to optimizer to decide whether to use an index or full-table scan or help the optimizer determine the fastest table join order. Incorrect: A: 100 is the maximum value ofoptimizer_index_cost_adj Note:OPTIMIZER_INDEX_COST_ADJ lets you tune optimizer behavior for access path selection to be more or less index friendly that is, to make the optimizer more or less prone to selecting an index access path over a full table scan. The default for this parameter is 100 percent, at which the optimizer evaluates index access paths at the regular cost. Any other value makes the optimizer evaluate the access path at that percentage of the regular cost. For example, a setting of 50 makes the index access path look half as expensive as normal. B:DB_FILE_MULTIBLOCK_READ_COUNTdoes not apply: DB_FILE_MULTIBLOCK_READ_COUNT is one of the parameters you can use to minimize I/O during table scans. It specifies the maximum number of blocks read in one I/O operation during a sequential scan. The total number of I/Os needed to perform a full table scan depends on such factors as the size of the table, the multiblock read count, and whether parallel execution is being

56 utilized for the operation. F: High (not low) row per block could make a table scan preferable. QUESTION 48 You have created some materialized views to improve the performance of several queries. Which four must be true to enable sessions to benefit from improved response time made possible by these materialized views? A. Query rewrite must be enabled for the sessions. B. Bitmap indexes must exist on all the columns involved in the join operations for the defining query of the MVIEWs. C. All or part of the query results must be obtainable from one or more MVIEWs. D. Bitmap join indexes must exist on all the columns involved in the join operations. E. Session users must have query rewrite privilege. F. The MVIEWs must be enabled for query rewrite. G. All or part of the query results must be obtainable from one MVIEW. Correct Answer: ABCF /Reference: A:For a given user's session, ALTER SESSION can be used to disable or enable query rewrite for that session only. B: Bitmap indexes on the join columns would improve performance. C(notG) :One of the major benefits of creating and maintaining materialized views is the ability to take advantage of query rewrite, which transforms a SQL statement expressed in terms of tables or views into a statement accessing one or more materialized views that are defined on the detail tables. F: *A materialized view is only eligible for query rewrite if the ENABLE QUERY REWRITE clause has been specified, either initially when the materialized view was first created or subsequently with an ALTER MATERIALIZED VIEW statement. *Enabling or disabling query rewrite: by the CREATE or ALTER statement for individual materialized views by the initialization parameter QUERY_REWRITE_ENABLED by the REWRITE and NOREWRITE hints in SQL statements Note: *A materialized view is a replica of a target master from a single point in time. The master can be either a master table at a master site or a master materialized view at a materialized view site. Whereas in multimaster replication tables are continuously updated by other master sites, materialized views are updated from one or more masters through individual batch updates, known as a refreshes, from a single master site or master materialized view site. QUESTION 49 View the code sequence:

57 Which three statements are true about the execution of this query? A. The optimizer uses an index join as an access path. B. The optimizer uses a B* tree access path for the EMPLOYEES table. C. The optimizer uses a bitmap access path for the EMPLOYEES table. D. The optimizer performs bitmap conversion fromrow IDs. E. The optimizer performs bitmap conversion to row IDs of the combined maps. F. The optimizer performs bitmap conversion from the row IDs of the combined maps. Correct Answer: ACF /Reference: C:The INDEX_COMBINE hint explicitly chooses a bitmap access path for the table. F:If you specify indexspec, then the optimizer tries to use some Boolean combination of the specified indexes. Each parameter serves the same purpose as in "INDEX Hint". For example: SELECT /*+ INDEX_COMBINE(e emp_manager_ix emp_department_ix) */ * FROM employees e WHERE manager_id = 108 OR department_id = 110; QUESTION 50 View the code sequence:

58 Examine the Exhibit to view the execution plan. Which two statements are true about the query execution? Exhibit:

59 A. The optimizer joins specified tables in the order as they appear in the FROM clause. B. The CUSTOMERS and ORDERS tables are joined first and the resultant is then joined with rows returned by the ORDER_ITEMS table. C. The CUSTOMERS and ORDER_ITEMS tables are joined first the resultant is then joined with rows by the ORDERS table. D. The optimizer has chosen hash join as an access method as the OPTIMIZER_MODE parameter is set to FIRST_ROWS. Correct Answer: CD /Reference: The first executed join is in line 6. The second executed join is in line 1. Incorrect: A: Line 7 and 8 are executed first. QUESTION 51 Examine the parallelism parameters for your instance:

60 What are true about the execution of the query? A. It will execute in parallel only if the LINEITEM table has a dictionary DOP defined. B. DOP for the statement is determined by the dictionary DOP of the accessed objects. C. It is generated to execute in parallel. D. It will execute in parallel only if the estimated execution time is 10 or more seconds. E. DOP for the statement is calculated automatically. F. It may execute serially. Correct Answer: EF /Reference: E: F (not C): It may execute serially. See note below. Incorrect: A, B: Dictionary DOP not used with PARALLEL (AUTO) hint. D: The default value of parallel_min_time_threshold is 30 (not 10) seconds. Note: * parallel_min_percent PARALLEL_MIN_PERCENT operates in conjunction with PARALLEL_MAX_SERVERS and PARALLEL_MIN_SERVERS. It lets you specify the minimum percentage of parallel execution processes (of the value of PARALLEL_MAX_SERVERS) required for parallel execution. Setting this parameter ensures that parallel operations will not execute sequentially unlessadequate resources are available. The default value of 0 means that no minimum percentage of processes has been set.

61 Consider the following settings: PARALLEL_MIN_PERCENT = 50 PARALLEL_MIN_SERVERS = 5 PARALLEL_MAX_SERVERS = 10 If 8 of the 10 parallel execution processes are busy, only 2 processes are available. If you then request a query with a degree of parallelism of 8, the minimum 50% will not be met. QUESTION 52 You execute the following query: Which statement is true about the usage of these hints in the query? A. The optimizer pushes the join predicate into the inline view. B. The optimizer evaluates the subquery as a first and then filters out rows. C. The optimizer performs a join operation first and then filters out the rows. D. The hint will have no effect because one of the join resultsets is an inline view. Correct Answer: A /Reference: The PUSH_PRED hint forces pushing of a join predicate into the view. For example: SELECT /*+ NO_MERGE(v) PUSH_PRED(v) */ * FROM employees e, (SELECT manager_id FROM employees ) v WHERE e.manager_id = v.manager_id(+) AND e.employee_id = 100; When the PUSH_PRED hint is used without an argument, it should be placed in the view query block. When PUSH_PRED is used with the view name as an argument, it should be placed in the surrounding query. Reference:Oracle Database Performance Tuning Guide,PUSH_PRED QUESTION 53 You notice some performance degradation for a high-load SQL statement in your database. After investigations, you run the SQL Tuning Advisor, which recommends a SQL Profile. You accept the profile recommendation resulting in a new, tuned execution plan for the statement. Your database uses SQL plan management and a SQL plan baseline exists for this SQL statement.

62 Which statement is true? A. The database adds the tuned plan to the SQL plan baseline as a nonfixed plan. B. The database adds the tuned plan to the SQL plan baseline as a fixed plan. C. The optimizer uses the new tuned plan only when a reproducible fixed plan is present. D. The created SQL profile will continuously adapt to all changes made to the database, the object, and to the system statistics over an extended length of time. Correct Answer: A /Reference: Note: *When the SQL Tuning Advisor recommends that a SQL Profile be used, you should accept the SQL Profile that is recommended. In cases where the SQL Tuning Advisor recommends that an index and a SQL Profile be used, both should be used. You can use the DBMS_SQLTUNE.ACCEPT_SQL_PROFILE procedure to accept a SQL Profile recommended by the SQL Tuning Advisor. This creates and stores a SQL Profile in the database. *When tuning SQL statements with the SQL Tuning Advisor, if the advisor finds a tuned plan and verifies its performance to be better than a plan chosen from the corresponding SQL plan baseline, it makes a recommendation to accept a SQL profile. When the SQL profile is accepted, the tuned plan is added to the corresponding SQL plan baseline. *If SQL plan management is used and there is already an existing plan baseline for the SQL statement, a new plan baseline will be added when a SQL profile is created. *SQL plan management is a preventative mechanism that records and evaluates the execution plans of SQL statements over time, and builds SQL plan baselines composed of a set of existing plans known to be efficient. The SQL plan baselines are then used to preserve performance of corresponding SQL statements, regardless of changes occurring in the system. *SQL plan baseline is fixed if it contains at least one enabled plan whose FIXED attribute is set to YES. *ACCEPT_SQL_PROFILE Procedure and Function This procedure creates a SQL Profile recommended by the SQL Tuning Advisor. The SQL text is normalized for matching purposes though it is stored in the data dictionary in de-normalized form for readability. QUESTION 54 Examine the initialization parameters for a database an OLTP overload.

63 What is the effect of changing the value of the parameter? A. It influences the optimizer to always use the value of the parameter? B. It influences the optimizer to use indexes instead of full table scans as the estimated cost ofthe using index is reduced. C. It influences the optimizer to use full table scans instead of index scans as the estimated cost of full table scan is reduced. D. It influenced the optimizer to use bitmap indexes as the estimated cost conversion from bimap is rowed us reduced. Correct Answer: B /Reference: OPTIMIZER_INDEX_COST_ADJ OPTIMIZER_INDEX_COST_ADJ lets you tune optimizer behavior for access path selection to be more or less index friendly that is, to make the optimizer more or less prone to selecting an index access path over a full table scan. The default for this parameter is 100 percent, at which the optimizer evaluates index access paths at the regular cost. Any other value makes the optimizer evaluate the access path at that percentage of the regular cost. For example, a setting of 50 makes the index access path look half as expensive as normal. QUESTION 55 You executed the following statements: Which two statements are true about the query execution?

64 A. The execution plan is generated and fetched from the library cache. B. The query executes and displays the execution plan and statistics. C. The query executes and inserts the execution plan in PLAN_TABLE. D. The query executes and execution plan is stored in the library cache and can be viewed using v$sql_plan. E. The query will always use the plan displayed by the AUTOTRACE output. Correct Answer: BE /Reference: B: set autotrace traceonly:displays the execution plan and the statistics (as set autotrace on does), but doesn't print a query's result. Note: /Autotrace Autotrace can be configured to run the SQL & gives a plan and statistics afterwards or just give you an explain plan without executing the query. To achieve this use the following: *Explain only set autotrace traceonly explain *Execute with stats and explain plan set autotrace on explain stat (with data returned by query) or autotrace traceo expl stat (without data returned by query) *To make the output from an autotrace more readable col plan_plus_exp format a100 *Turn off autotrace set autotrace off /V$SQL_PLAN contains the execution plan information for each child cursor loaded in the library cache. QUESTION 56 How can you reduce fragmentation of an index without affecting the current transactions that are using the index? A. Use the ANALYZE INDEX... command B. Use the ALTER INDEX... VALIDATE STRUCTURE command C. Use the ALTER INDEX... REBUILD ONLINE command D. Use the ALTER INDEX... DEALLOCATE UNUSED command Correct Answer: D /Reference: Use the deallocate_unused_clause to explicitly deallocate unused space at the end of the index and make the freed space available for other segments in the tablespace. If index is range-partitioned or hash-partitioned, then Oracle Database deallocates unused space from each index partition. If index is a local index on a composite-partitioned table, then Oracle Database deallocates unused space from each index subpartition. Reference: OracleDatabase SQL Language Reference11g, alter index QUESTION 57

65 Examine the Following Query and execution plan:

66

67 Which query transformation technique is used by the optimizer? A. Filter push down B. Subquery factoring C. Subquery unnesting D. Predicate pushing Correct Answer: D /Reference: Note: *In the execution plan BX, note the keyword 'VIEW PUSHED PREDICATE' indicates that the view has undergone the join predicate pushdown transformation. QUESTION 58 Examine the Exhibit and view the structure of an indexes for the EMPLOYEES table. Which two actions might improve the performance of the query? Exhibit:

68 A. Use the ALL_ROWS hint in the query. B. Collect the histogram statistics for the EMPLOYEE_ID column. C. Decrease the value for the DB_FILE_MULTIBLOCK_READ_COUNT initialization parameter. D. Decrease the index on the EMPLOYEE_ID if not being used. E. Set the OPTIMIZER_MODE parameter to ALL_ROWS. Correct Answer: AE /Reference: A:The ALL_ROWS hint instructs the optimizer to optimize a statement block with a goal of best throughput, which is minimum total resource consumption. E:optimizer_mode=all_rows - This optimizer mode favors full-table scans (especially parallel full-table-scans) in cases where the server resources will be minimized. The all_rows mode is generally used during batch-oriented processing and for data warehouses where the goal is to minimize server resource consumption. QUESTION 59 Examine the parallel parameters for your instance.

69 All parallel execution servers are available and the session use default parallelism settings. In which two cases will the degree of parallelism be automatically calculated? A. Statements accessing tables whom dictionary DOP is 2 or more B. Statements accessing tables whose dictionary DOP is DEFAULT C. Statements that are estimated to execute for more than 10 seconds serially D. Statements accessing tables with any setting for Dictionary DOP E. Statements with parallel hints Correct Answer: BE /Reference: Note:In earlier versions of the Oracle Database, we had to determine the DOP more or less manually, either with a parallel hint or by setting a parallel degree with alter table. There was an automatic computation of the DOP available for the objects with dictionary DOP of default, derived from the simple formula CPU_COUNT * PARALLEL_THREADS_PER_CPU. QUESTION 60 A database instance is configured in the shared server mode and it supports multiple applications running on a middle tier. These applications connect to the database by using different services and tracing is enabled for the services. You want to view the detailed tracing setting for particular service. What would you use to view the tracing information? A. DBMS_SERVICE package B. DBMS_MONITOR package

70 C. DBA_ENABLED_TRACES view D. Trcsess and tkprof Correct Answer: C /Reference: DBA_ENABLED_TRACES displays information about enabled SQL traces. Incorrect: A:The DBMS_SERVICE package lets you create, delete, activate, and deactivate services for a single instance. B:The DBMS_MONITOR package let you use PL/SQL for controlling additional tracing and statistics gathering. Reference: OracleDatabase Reference,DBA_ENABLED_TRACES QUESTION 61 Examine the statements being executed for the first time: Steps followed by a SQL statement during parsing: 1. Search for a similar statement in the shared pool. 2. Search for an identical statement in the shared pool. 3. Search the SQL area of identical statement already in the shared pool. 4. Proceed through the remaining steps of the parse phase to ensure that the execution plan of the existing statements is applicable to the view statement. 5. Perform hard parsing. 6. Share the SQL area of the similar statement already in the shared pool. Identify the required steps in the correct sequence used by the third query. A. 5, 1, 3, 4 B. 2, 4, 3 C. 5, 2, 3, 4 D. 1, 4, 3 E. Only 5 F. 2, 5 Correct Answer: F /Reference: 2) before 5). Note:

71 *When application code is run, Oracle attempts to reuse existing code if it has been executed previously and can be shared. If the parsed representation of the statement does exist in the library cache and it can be shared, then Oracle reuses the existing code. This is known as a soft parse, or a library cache hit. If Oracle is unable to use existing code, then a new executable version of the application code must be built. This is known as a hard parse, or a library cache miss. Reference:Oracle Database Performance Tuning Guide,SQL Sharing Criteria QUESTION 62 You execute the following query for the first time: Examine the SQL statement processing steps: 1. The value of the variable SAL is obtained to run the query. 2. The syntax of the query is checked 3. A parse tree for the query is generated 4. Semantics for the query are checked 5. The required rows are fetched 6. The SQL is executed to produce the required result. Which is the correct order of execution of the above query? A. 1, 2 3, 4, 5, 6 B. 1, 4, 2, 3, 6, 5 C. 2, 4, 1, 3, 6, 5 D. 2, 3, 1, 4, 6, 5 Correct Answer: D /Reference: Incorrect: A: First execute then fetch rows. B: Check of syntax is before check of semantics. C: Parse tree is before semantics. QUESTION 63 You plan to bulk load data using INSERT /*+PARALLEL*/ INTO.... SELECT FROM statements. Which four types of operations can execute in parallel on tables that have no bitmapped indexes or materialized views defined on term? A. Direct path insert of a million rows into a partitioned, index-organized table containing one million rows. B. Direct path insert of a million rows into a partitioned, index-organized table containing 10 million rows. C. Direct path insert of a million rows into a nonpartitioned, index-organized table containing one million rows. D. Direct path insert of a million rows into a nonpartitioned, heap-organized table containing 10

72 million rows. E. Direct path insert of a million rows into a nonpartitioned, heap-organized table containing one million rows. Correct Answer: ABDE /Reference: Direct-path INSERT is not supported for an index-organized table (IOT) if it is not partitioned, if it has a mapping table, or if it is reference by a materialized view. QUESTION 64 Which three options are true about parallel queries when PARALLEL_DEGREE_POLICY is set to MANUAL and the session is using the default settings for parallel query, DDL, and DML? A. A subquery in a parallel DML isparallelizedonly if it includes a parallel hint. B. The number of parallel execution servers requested for a cursor is based on the greatest degree of parallelism associated with any object accessed by the cursor. C. A SELECT statement can be executed in parallel only if no scalar subqueries are contained in the SELECT list. D. In a CREATE TABLE... AS SELECT (CTAS) statement, SELECT is parallelized only if create TABLE is parallelized. E. In an INSERT INTO... SELECT FROM statement, INSERT is parallelized if select is parallelized. F. Single row inserts are never executed is parallel. Correct Answer: CEF /Reference: *Decision to Parallelize A SELECT statement can be parallelized only if the following conditions are satisfied: /The query includes a parallel hint specification (PARALLEL or PARALLEL_INDEX) or the schema objects referred to in the query have a PARALLEL declaration associated with them. /At least one of the tables specified in the query requires one of the following: A full table scan An index range scan spanning multiple partitions / (C)No scalar subqueries are in the SELECT list. *By default, the system only uses parallel execution when a parallel degree has been explicitly set on an object or if a parallel hint is specified in the SQL statement. *CREATE TABLE... AS SELECT in Parallel Parallel execution lets you parallelize the query and create operations of creating a table as a subquery from another table or set of tables. This can be extremely useful in the creation of summary or rollup tables. Clustered tables cannot be created and populated in parallel. *PARALLEL_DEGREE_POLICY specifies whether or not automatic degree of Parallelism, statement queuing, and in-memory parallel execution will be enabled.

73 MANUAL Disables automatic degree of parallelism, statement queuing, and in-memory parallel execution. This reverts the behavior of parallel execution to what it was prior to Oracle Database 11g Release 2 (11.2). This is the default. Incorrect: A: *For parallel DML (INSERT, UPDATE, MERGE, and DELETE), the reference object that determines the DOP(degree of parallelism)is the table being modified by and insert, update, or delete operation. Parallel DML also adds some limits to the DOP to prevent deadlock. If the parallel DML statement includes a subquery, the subquery's DOP is the same as the DML operation. *For parallel DDL, the reference object that determines the DOP is the table, index, or partition being created, rebuilt, split, or moved. If the parallel DDL statement includes a subquery, the subquery's DOP is the same as the DDL operation. D:The CREATE TABLE... AS SELECT statement contains two parts: a CREATE part (DDL) and a SELECT part (query). Oracle Database can parallelize both parts of the statement. The query part of a CREATE TABLE... AS SELECT statement can be parallelized only if the following conditions are satisfied: Reference: OracleDatabase VLDB and Partitioning Guide,Using Parallel Execution QUESTION 65 A table has three distinct values in its ID column. In the ID column, values 10 and 20 have more than rows each and value 30 has only five rows. The statistics for the schema have been updated recently. The CURSOR_SHARING parameter is set to EXACT. The query was executed recently and the cursor for the query is bind aware. Examine the exhibits to view the commands executed. You plan to execute the same query with a value of 30 for the bind variable V_ID. Which statement is true in this scenario? Exhibit:

74 A. The same execution plan will always be used irrespective of the value in the bind variable. B. A new execution plan will be generated depending on the access pattern and the bind value. C. Adaptive cursor sharing will ensure that a new cursor is generated for each distinct value in the bind variable. D. Adaptive cursor sharing will happen only if you use the literal values instead of bind variables in the query. Correct Answer: C /Reference: Note: *CURSOR_SHARING determines what kind of SQL statements can share the same cursors.

75 *Setting CURSOR_SHARING to EXACT allows SQL statements to share the SQL area only when their texts match exactly. This is the default behavior. Using this setting, similar statements cannot shared; only textually exact statements can be shared. *Values: * FORCE Forces statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect the meaning of the statement. * SIMILAR Causes statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect either the meaning of the statement or the degree to which the plan is optimized. * EXACT Only allows statements with identical text to share the same cursor. QUESTION 66 See the table below: All parallel execution servers are available and sessions use default settings for parallelism. Which three are true about parallel execution in your instance? A. Parallel execution occurs when estimated serial execution time exceeds the minimum time threshold. B. Parallel execution occurs for all DML statements. C. Parallel execution occurs for those statements that access tables with dictionary DOP defined. D. Parallel execution occurs for those statements that access tables with no dictionary DOP defined. E. Parallel execution occurs for all DDL statements. Correct Answer: ACD /Reference:

76 A(not B, Not E):PARALLEL_MIN_TIME_THRESHOLD : Oracle 11gR2 will ascertain if the query s estimated execution time is likely to run longer than the acceptable value (in seconds) for parallel_min_time_threshold and, if sufficient resources for parallel execution exist right now, it will allow the query to execute; otherwise, it will delay its execution until sufficient resources exist. This helps prevent a single parallel query from consuming excessive resources at the cost of other non-parallelizable operations.the default of this parameter is 10 seconds. C, D:In earlier versions of the Oracle Database, we had to determine the DOP more or less manually, either with a parallel hint or by setting a parallel degree with alter table. There was an automatic computation of the DOP available for the objects with dictionary DOP of default, derived from the simple formula CPU_COUNT * PARALLEL_THREADS_PER_CPU. If there were insufficient parallel servers to satisfy the requested DOP, one of three things could occur: /The SQL would be run at a reduced DOP (be downgraded) /The SQL would run in serial mode (be serialized) /If PARALLEL_MIN_PERCENT was specified and less than the nominated percentage of the DOP was achievable, then the the SQL statement might terminate with "ORA-12827: insufficient parallel query slaves available". Note: *PARALLEL_DEGREE_POLICY. It can have 3 values : MANUAL, LIMITED and AUTO MANUAL - This is the default. Disables Auto DOP, statement queuing and in-memory parallel execution. It reverts the behavior of parallel execution to what it was previous to Oracle Database 11g, Release 2 (11.2). *Oracle supports parallel processing for a wide range of operations, including queries, DDL and DML: Queries that involve table or index range scans. Bulk insert, update or delete operations. Table and index creation. *Oracle's parallel execution framework enables you to either explicitly chose - or even enforce - a specific degree of parallelism (DOP) or to rely on Oracle to control it. *Three modes are available to request a DOP : default fixed adaptive *The DOP is determined in the following priority order: hint session table and limited by the Oracle Database Resource Manager (DBRM) settings. Reference:AUTOMATIC DEGREE OF PARALLELISM (DOP) IN ORACLE 11G R2 QUESTION 67 An application issues many expensive join aggregations type queries. Examine the Exhibit to view the queries. Which two could help improve the performance of these SQL statements without changing application code? Exhibit:

77 A. Create B*-Tree indexes on the join columns. B. Create a materialized view with query rewrite enabled for the first statement and nested MVIEWs for the other statements. C. Collect histogram statistics on columns for which aggregating functions are performed. D. Create an STS for these queries and use SQL Access Advisor, which may generate advice about MVIEWs. E. Create an STS for these queries and use SQL Performance Analyzer, which may generate advice about MVIEWs. Correct Answer: BD /Reference: B:Materialized views and indexes are essential when tuning a database to achieve optimum performance for complex, data-intensive queries.

78 D: * STS SQL tuning set. *A SQL Tuning Set is a database object that includes one or more SQL statements and their execution statistics and execution context. You can use the set as an input source for various advisors, such as SQL Tuning Advisor, SQL Access Advisor, and SQL Performance Analyzer. * SQL Access Advisor: Materialized views and indexes are essential when tuning a database to achieve optimum performance for complex, data-intensive queries. The SQL Access Advisor helps you achieve your performance goals by recommending the proper set of materialized views, materialized view logs, and indexes for a given workload. Understanding and using these structures is essential when optimizing SQL as they can result in significant performance improvements in data retrieval. The advantages, however, do not come without a cost. Creation and maintenance of these objects can be time consuming, and space requirements can be significant. The SQL Access Advisor recommends bitmap, function-based, and B-tree indexes. A bitmap index offers a reduced response time for many types of ad hoc queries and reduced storage requirements compared to other indexing techniques. B-tree indexes are most commonly used in a data warehouse to index unique or near-unique keys. Note: *Conventional wisdom holds that bitmap indexes are most appropriate for columns having low distinct values--such as GENDER, MARITAL_STATUS, and RELATION. This assumption is not completely accurate, however. In reality, a bitmap index is always advisable for systems in which data is not frequently updated by many concurrent systems.abitmap index on a column with 100- percent unique values (a column candidate for primary key) is as efficient as a B-tree index. *By default, the Oracle creates a b_tree index. In a b-tree, you walk the branches until you get to the node that has the data you want to use. In the classic b-tree structure, there are branches from the top that lead to leaf nodes that contain the data. Incorrect: not E:SQL Performance Analyzer enables you to assess the performance impact of any system change resulting in changes to SQL execution plans and performance characteristics. Examples of common system changes for which you can use SQL Performance Analyzer include: Database upgrade Configuration changes to the operating system, hardware, or database Database initialization parameter changes Schema changes, for example, adding new indexes or materialized views Gathering optimizer statistics Validating SQL tuning actions, for example, creating SQL profiles or implementing partitioning QUESTION 68 View the exhibit and examine the findings provided by the SQL Tuning Advisor for SELECT Statement. A SWL plan baseline already exists for the execution plan. What two methods can you use to ensure that an alternate plan becomes an accepted plan? Exhibit:

79 A. Use the DBMS_SPM.ALTER_SQL_PLAN_BASELINE function. B. Use the DBMS_SQLTUNE.CREATE_SQL_PLAN_BASELINE function. C. Use the DBMS_SQLTUNE.CREATE_SQL_PLAN_BASELINE function and run the DBMS_STATS to manually refresh stale statistics. D. Use the DBMS_SPM.LOAD_PLANS_FROM_SQLSET function. Correct Answer: CD /Reference: C:To adopt an alternative plan regardless of whether SQL Tuning Advisor recommends it, call DBMS_SQLTUNE.CREATE_SQL_PLAN_BASELINE. You can use this procedure to create a SQL plan baseline on any existing reproducible plan. D:LOAD_PLANS_FROM_SQLSET Function This function loads plans stored in a SQL tuning set (STS) into SQL plan baselines. The plans loaded from STS are not verified for performance but added as accepted plans to existing or new SQL plan baselines. This procedure can be used to seed SQL management base with new SQL plan baselines. Note: *While tuning a SQL statement, SQL Tuning Advisor searches real-time and historical performance data for alternative execution plans for the statement. If plans other than the original plan exist, then SQL Tuning Advisor reports an alternative plan finding. SQL Tuning Advisor validates the alternative execution plans and notes any plans that are not reproducible. When reproducible alternative plans are found, you can create a SQL plan baseline to instruct the optimizer to choose these plans in the future.

80 Incorrect: Not A:ALTER_SQL_PLAN_BASELINE Function This function changes an attribute of a single plan or all plans associated with a SQL statement using the attribute name/value format. Usage Notes When a single plan is specified, one of various statuses, or plan name, or description can be altered. When all plans for a SQL statement are specified, one of various statuses, or description can be altered. This function can be called numerous times, each time setting a different plan attribute of same plan(s) or different plan(s). Reference:Oracle Database Performance Tuning Guide,Alternative Plan Analysis QUESTION 69 You ran a high load SQL statement that used an index through the SQL Tuning Advisor and accepted its recommendation for SQL profile creation. Subsequently you noticed that there has been a 2% growth in number of rows in the tables used by the SQL statement and database statistics have also been refreshed. How does this impact the created SQL profile? A. It becomes invalid and no longer used the optimizer. B. It remains valid and ensures that the optimizer always use the execution plan that was created before the changes happened. C. It remains and allows the optimizer to pick a different plan required. D. It becomes invalid and a new SQL profile is created for the statement by the auto tuning task. Correct Answer: C /Reference: QUESTION 70 Auto DOP is enabled for your instance. You execute the following statements: Which three are true about the execution of the join? A. Dictionary DOP is usedto calculate statements DOP B. Hinted DOP is used to calculate statement DOP. C. TheEMPLOYEEStableis accessed in parallel. D. The DEPARTMENTS table is accessedin parallel.

81 E. The hint operates atthe level of each table accessed by the statement. Correct Answer: BCE /Reference: C: As peralter TABLE employees PARALLEL 2; Incorrect: not D: As peralter TABLE departments NOPARALLEL; QUESTION 71 Which two statements are true about the trcsess utility? A. It merges multiple trace files and produces a formatted output file. B. It merges multiple trace files from a particular session into one single trace file. C. It produces multiple files only for DBA sessions, which can be consolidated into one formatted file using the tkprof utility. D. It produces multiple files for a service, which can be consolidated into one formatted file using the tkprof utility. E. It merges files pertaining to a user session scattered across different processes in a shared server configuration. Correct Answer: AB /Reference: The trcsess utility consolidates trace output from selected trace files based on several criteria: Session ID Client ID Service name Action name Module name After trcsess merges the trace information into a single output file, the output file could be processed by TKPROF. Note: *trcsess is useful for consolidating the tracing of a particular session for performance or debugging purposes. Tracing a specific session is usually not a problem in the dedicated server model as a single dedicated process serves a session during its lifetime. You can see the trace information for the session from the trace file belonging to the dedicated server serving it. However, in a shared server configuration a user session is serviced by different processes from time to time. The trace pertaining to the user session is scattered across different trace files belonging to different processes. This makes it difficult to get a complete picture of the life cycle of a session. Reference:Oracle Database Performance Tuning Guide11g,Using the trcsess Utility * Now there is a new tool, a command line utility called trcsess to help read the trace files. The trcsess command-line utility consolidates trace information from selected trace files, based on specified criteria. The criteria include session id, client id, service name, action name and module name. QUESTION 72 The following parameter values are set for the instance:

82 OPTIMIZER_CAPTURE_SQL_BASELINE = FALSE OPTIMIZER_USESQL_PLAN_BASELINE = TRUE The SQL plan baseline for a SQL statement contains an accepted plan. You want to add a new plan automatically as an accepted plan to the existing SQL plan baseline. Examine the following tasks. 1. Set the OPTIMIZER_CAPTURE_SQL_PLAN_BASELINE parameter to TRUE. 2. Evolve the new plan. 3. Fix the existing accepted plan. 4. Manually load the new plan. Identify the task(s) that must be performed to accomplish this. A. 1, 2, and 3 B. 4 and 3 C. 1, 4, and 3 D. Only 4 E. 1, 2, 4, and 3 F. 1 and 2 Correct Answer: D /Reference: Manual Plan Loading Manual plan loading can be used in conjunction with, or as an alternative to automatic plan capture. The load operations are performed using the DBMS_SPM package, which allows SQL plan baselines to be loaded from SQL tuning sets or from specific SQL statements in the cursor cache. Manually loaded statements are flagged as accepted by default. If a SQL plan baseline is present for a SQL statement, the plan is added to the baseline, otherwise a new baseline is created. Note: *The value of the OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES parameter, whose default value is FALSE, determines if the system should automatically capture SQL plan baselines. When set to TRUE, the system records a plan history for SQL statements. The first plan for a specific statement is automatically flagged as accepted. Alternative plans generated after this point are not used until it is verified they do not cause performance degradations. Plans with acceptable performance are added to the SQL plan baseline during the evolution phase. *Managing SQL plan baselines involves three phases: Capturing SQL Plan Baselines Selecting SQL Plan Baselines Evolving SQL Plan Baselines *Evolving SQL Plan Baselines Evolving a SQL plan baseline is the process by which the optimizer determines if non-accepted plans in the baseline should be accepted. As mentioned previously, manually loaded plans are automatically marked as accepted, so manual loading forces the evolving process. When plans are loaded automatically, the baselines are evolved using the EVOLVE_SQL_PLAN_BASELINE function, which returns a CLOB reporting its results.

83 Reference:SQL Plan Management in Oracle Database 11g Release 1 QUESTION 73 Examine the Exhibit and view the query and its execution plan. Which statement is correct about the parallel executions plan? Exhibit:

84 A. The CUSTOMERS and SALES tables are scanned simultaneously in parallel and then joined in parallel. B. First, the CUSTOMERS table is scanned in parallel, then the SALES table is scanned in parallel, and then they are joined serially. C. First, the SALES table is scanned in parallel, then the CUSTOMERS table us scanned in parallel, and then they are joined in parallel. D. The CUSTOMERS and SALES tables are scanned simultaneously in parallel and then joined serially. E. First, the CUSTOMERS table is scanned in parallel, then the SALES table us scanned in parallel, and then they are joined in parallel. Correct Answer: D

85 /Reference: As per exhibit: Line 7 and line 11 are run in parallel. Line 8 and line 12 are run in parallel. Line 9 and line 13 are run in parallel. Line 10 and line 14 are run in parallel. Line 6 serially joins the two parallel scan (resulting from line 7 and 11). Note: * PX BLOCK ITERATOR The PX BLOCK ITERATOR row source represents the splitting up of the table EMP2 into pieces so as to divide the scan workload between the parallel scan slaves. QUESTION 74 Which three statements are true the Automatic Tuning Optimizer (ATO)? A. It identifies the objects with stale or missing statistics and gathers statistics automatically. B. It investigates the effect of new or modified indexes on the access paths for a workload and recommends running that statistics through the SQL Access Advisor. C. It recommends a SQL profile to help create a better execution plan. D. It picks up resource-intensive SQL statements from the ADDM and recommends the use of materialized views to improve query performance. E. It identifies the syntactic, semantic, or design problems with structure of SQL statements leading to poor performance and suggests restricting the statements. F. It identifies resource-intensive SQL statements, runs them through the SQL Tuning Advisor, and implements the recommendations automatically. Correct Answer: ADF /Reference: ----MI DAVA D,F---- Under tuning mode, the optimizer can take several minutes to tune a single statement. It is both time and resource intensive to invoke Automatic Tuning Optimizer every time a query must be hard-parsed. Automatic Tuning Optimizer is meant for complex and high-load SQL statements that have nontrivial impact on the database. Automatic Database Diagnostic Monitor (ADDM) proactively identifies high-load SQL statements that are good candidates for SQL tuning (see Chapter 6, "Automatic Performance Diagnostics"). The automatic SQL tuning feature also automatically identifies problematic SQL statements and implements tuning recommendations during system maintenance windows as an automated maintenance task. The Automatic Tuning Optimizer performs the following types of tuning analysis: Statistics Analysis SQL Profiling Access Path Analysis SQL Structure Analysis Alternative Plan Analysis Note: *Oracle Database uses the optimizer to generate the execution plans for submitted SQL statements. The optimizer operates in the following modes:

86 Normal mode The optimizer compiles the SQL and generates an execution plan. The normal mode generates a reasonable plan for the vast majority of SQL statements. Under normal mode, the optimizer operates with very strict time constraints, usually a fraction of a second. Tuning mode The optimizer performs additional analysis to check whether it can further improve the plan produced in normal mode. The optimizer output is not an execution plan, but a series of actions, along with their rationale and expected benefit for producing a significantly better plan. When running in tuning mode, the optimizer is known as the Automatic Tuning Optimizer. QUESTION 75 In your database, the CURSOR_SHARING parameter is set to FORCE. A user issues the following SQL statement: Select * from SH.CUSTOMERS where REIGN= NORTH Which two statements are correct? A. The literal value NORTH is replaced by a system-generated bind variable. B. Bind peeking will not happen and subsequent executions of the statement with different literal values will use the same plan. C. Adaptive cursor sharing happens only if there is a histogram in the REIGN column of the CUSTOMERS table. D. Adaptive cursor sharing happens irrespective of whether there is a histogram in the REIGN column of the CUSTOMERS table. Correct Answer: AB /Reference: CURSOR_SHARING determines what kind of SQL statements can share the same cursors. Values: * FORCE Forces statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect the meaning of the statement. * SIMILAR Causes statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect either the meaning of the statement or the degree to which the plan is optimized. * EXACT Only allows statements with identical text to share the same cursor. QUESTION 76 Examine Exhibit 1 to view the query and its execution plan. Examine Exhibit 2 to view the structure and indexes for the EMPLOYEES and DEPARTMENTS tables. Examine Exhibit 3 to view the initialization parameters for the instance. Why is sort-merge join chosen as the access method?

87 76_1 (exhibit):

88

89 76_2 (exhibit): 76_3 (exhibit):

90 A. Because the OPTIMIZER_MODE parameter is set to ALL_ROWS. B. Because of an inequality condition. C. Because the data is not sorted in the LAST_NAME column of the EMPLOYEES table D. Because of the LIKE operator used in the query to filter out records Correct Answer: A /Reference: Incorrect: B: There is not aninequality conditionin the statement. C: Merge joins are beneficial if the columns are sorted. D:All regular joins should be able to use Hash or Sort Merge, except LIKE,!=, and NOT... joins. Note: *A sort merge join is a join optimization method where two tables are sorted and then joined. *A "sort merge" join is performed by sorting the two data sets to be joined according to the join keys and then merging them together. The merge is very cheap, but the sort can be prohibitively expensive especially if the sort spills to disk. The cost of the sort can be lowered if one of the data sets can be accessed in sorted order via an index, although accessing a high proportion of blocks of a table via an index scan can also be very expensive in comparison to a full table scan. *Sort merge joins are useful when the join condition between two tables is an inequality condition (but not a nonequality) like <, <=, >, or >=. Sort merge joins perform better than nested loop joins for large data sets. You cannot use hash joins unless there is an equality condition. *When the Optimizer Uses Sort Merge Joins The optimizer can choose a sort merge join over a hash join for joining large amounts of data if any of the following conditions are true: /The join condition between two tables is not an equi-join. /Because of sorts already required by other operations, the optimizer finds it is cheaper to use a sort merge than a hash join. Reference: OracleDatabase Performance Tuning Guide,Sort Merge Joins QUESTION 77 Which four types of column filtering may benefit from partition pruning when accessing tables via

91 partitioned indexes? A. Equality operates on List-Partitioned Indexes B. Not Equal operates on a Global Hash-Partitioned Indexes C. Equality operates on System-Partitioned Tables D. In-List operates on Range-Partitioned Indexes E. Not Equal operates on a local Hash-Partitioned Indexes F. Equality operates on Range-Partitioned Indexes G. Equality operates on Hash-Partitioned Indexes Correct Answer: ADFG /Reference: Oracle Database prunes partitions when you use range, LIKE, equality(a, F), and IN-list(D)predicates on the range or list partitioning columns, and when you use equality(g)and INlist predicates on the hash partitioning columns. Reference:Oracle Database VLDB and Partitioning Guide11g,Information that can be Used for Partition Pruning QUESTION 78 You executed the following statement: Which three statements are true about EXPLAIN PLAN? A. The execution plan is saved in PLAN_TABLE without executing the query. B. The execution plan for the query is generated and displayed immediately as the output. C. The execution plan generated may not necessarily be the execution plan used during query execution. D. The execution plan is saved in DBA_HIST_SQL_PLAN without executing the query. E. The execution plan generated can be viewed using the DBMS_XPLAIN.DISPLAY function. F. The execution plan generated can be fetched from the library cache by using the DBMS_XPLAIN.DISPLAY function. Correct Answer: ACE /Reference: * (A, not D): The explain plan process stores data in the PLAN_TABLE. *EXPLAIN PLAN The EXPLAIN PLAN method doesn't require the query to be run(a), greatly reducing the time it takes to get an execution plan for long-running queries compared to AUTOTRACE. E: Use the DBMS_XPLAN.DISPLAY function to display the execution plan. *The DBMS_XPLAN package provides an easy way to display the output of the EXPLAIN PLAN

92 command in several, predefined formats. You can also use the DBMS_XPLAN package to display the plan of a statement stored in the Automatic Workload Repository (AWR) or stored in a SQL tuning set. It further provides a way to display the SQL execution plan and SQL execution runtime statistics for cached SQL cursors based on the information stored in the V$SQL_PLAN and V$SQL_PLAN_STATISTICS_ALL fixed views. Note: * First the query must be explained. SQL> EXPLAIN PLAN FOR 2 SELECT * 3 FROM emp e, dept d 4 WHERE e.deptno = d.deptno 5 AND e.ename = 'SMITH'; Explained. SQL> Then the execution plan displayed.(not B) Plan Table Operation Name Rows Bytes Cost Pstart Pstop SELECT STATEMENT NESTED LOOPS TABLE ACCESS FULL EMP TABLE ACCESS BY INDEX RO DEPT INDEX UNIQUE SCAN PK_DEPT rows selected. SQL> For parallel queries use the "utlxplp.sql" script instead of "utlxpls.sql". QUESTION 79 Which three factors does the estimator depend on for overall cost estimation of a given execution plan? A. Cardinality B. Sort area size C. OPTIMIZER_FEATURE_ENABLE parameter D. NOT NULL_FEATURE_ENABLE parameter E. NOT NULL constraint on a unique key column F. Library cache size G. The units of work such as disk input/output, CPU usage, and memory used in an operation Correct Answer: ACG /Reference: C:OPTIMIZER_FEATURES_ENABLE acts as an umbrella parameter for enabling a series of optimizer features based on an Oracle release number.

93 Note:The estimator determines the overall cost of a given execution plan. The estimator generates three different types of measures to achieve this goal: *Selectivity This measure represents a fraction of rows from a row set. The selectivity is tied to a query predicate, such as last_name='smith', or a combination of predicates. *Cardinality This measure represents the number of rows in a row set. 1, *Cost This measure represents units of work or resource used. The query optimizer uses disk I/O, CPU usage, and memory usage as units of work. If statistics are available, then the estimator uses them to compute the measures. The statistics improve the degree of accuracy of the measures. QUESTION 80 Examine the parallelism parameters for you instance. Now examine the DSS_PLAN with parallel statement directives:

94 Which two are true about the DSS_PLAN resource manager plan? A. URGENT_GROUPS sessions will always be dequeued before sessions from other groups. B. OTHER_GROUPS sessions are queued for maximum of six minutes. C. ETL_GROUP sessions can collectively consume 64 parallel execution servers before queuing starts for this consumer group. D. An ETL_GRP sessions will be switched to URGENT_GROUPS if the session requests more than eight parallel executions servers. E. URGENT_GROUP sessions will not be queued if 64 parallel execution servers are busy because their PARALLEL_TARGET_PERCENTAGE is not specified. Correct Answer: AB /Reference: B:PARALLEL_QUEUE_TIMEOUT Parallel Queue Timeout When you use parallel statement queuing, if the database does not have sufficient resources to execute a parallel statement, the statement is queued until the required resources become available. However, there is a chance that a parallel statement may be waiting in the parallel statement queue for longer than is desired. You can prevent such scenarios by specifying the maximum time a parallel statement can wait in the parallel statement queue. The PARALLEL_QUEUE_TIMEOUT directive attribute enables you to specify the maximum time, in seconds, that a parallel statement can wait in the parallel statement queue before it is timed out. The PARALLEL_QUEUE_TIMEOUT attribute can be set for each consumer group. Incorrect: Not C: ETL_GROUP PARALLEL_TARGET_PERCENTAGE is 50%. So ETL_GROUP can only consume 32 servers.

95 Note: *If you want more per-workload management, you must use the following directive attributes: /MGMT_Pn Management attributes control how a parallel statement is selected from the parallel statement queue for execution. You can prioritize the parallel statements of one consumer group over another by setting a higher value for the management attributes of that group. /PARALLEL_TARGET_PERCENTAGE /PARALLEL_QUEUE_TIMEOUT /PARALLEL_DEGREE_LIMIT_P1 * PARALLEL_DEGREE_LIMIT_P1 Degree of Parallelism Limit You can limit the maximum degree of parallelism for any operation within a consumer group. The degree of parallelism is the number of parallel execution servers that are associated with a single operation. Use the PARALLEL_DEGREE_LIMIT_P1 directive attribute to specify the degree of parallelism for a consumer group. The degree of parallelism limit applies to one operation within a consumer group; it does not limit the total degree of parallelism across all operations within the consumer group. However, you can combine both the PARALLEL_DEGREE_LIMIT_P1 and the PARALLEL_TARGET_PERCENTAGE directive attributes to achieve the desired control. * PARALLEL_TARGET_PERCENTAGE Parallel Target Percentage It is possible for a single consumer group to launch enough parallel statements to use all the available parallel servers. If this happens, when a high-priority parallel statement from a different consumer group is run, no parallel servers are available to allocate to this group. You can avoid such a scenario by limiting the number of parallel servers that can be used by a particular consumer group. Use the PARALLEL_TARGET_PERCENTAGE directive attribute to specify the maximum percentage of the parallel server pool that a particular consumer group can use. The number of parallel servers used by a particular consumer group is counted as the sum of the parallel servers used by all sessions in that consumer group. QUESTION 81 Which three statements are true about the usage of optimizer hints? A. Whenever a query uses table aliases, the hints in the query must use the aliases. B. The OPTIMIZER_FEATURES_ENABLE parameter must be set to a version supports the hints used. C. The optimizer uses the execution plan with lower cost even if a hint is specified. D. A schema name for the table must be used in the hint if the table is qualified in the FROM clause. E. Hints can be used to override the optimization approach specified with the OPTIMIZER_MODE parameter. F. A statement block can have only one hint, and that hint must be immediately after SELECT, UPDATE, INSERT, MERGE, or DELETE keyword. Correct Answer: ACE

96 /Reference: --MI DAVA A,E-- A:You must specify the table to be accessed exactly as it appears in the statement. If the statement uses an alias for the table, then use the alias rather than the table name in the hint. E:If a SQL statement has a hint specifying an optimization approach and goal, then the optimizer uses the specified approach regardless of the presence or absence of statistics, the value of the OPTIMIZER_MODE initialization parameter, and the OPTIMIZER_MODE parameter of the ALTER SESSION statement. Note: *Optimizer hints can be used with SQL statements to alter execution plans. *Hints let you make decisions usually made by the optimizer. As an application designer, you might know information about your data that the optimizer does not know. Hints provide a mechanism to instruct the optimizer to choose a certain query execution plan based on the specific criteria. For example, you might know that a certain index is more selective for certain queries. Based on this information, you might be able to choose a more efficient execution plan than the optimizer. In such a case, use hints to instruct the optimizer to use the optimal execution plan. *Hints apply only to the optimization of the block of a statement in which they appear. A statement block is any one of the following statements or parts of statements: A simple SELECT, UPDATE, or DELETE statement A parent statement or subquery of a complex statement A part of a compound query Reference:Oracle Database Performance Tuning Guide,Using Optimizer Hints QUESTION 82 Which three tasks are performed by the parallel execution coordinator process? A. Allocating parallel execution processes from the parallel execution server pool. B. Determining the parallel execution method for each operation in the execution plan. C. Managing the data flow between the producers and consumers during inter-operation parallelism. D. Any serial processing that is part of the execution plan. E. Determining the desired number of parallel execution processes F. Managing the data flow between the producers and consumers during intra-operation parallelism. Correct Answer: ABC /Reference: A:When executing a parallel operation, the parallel execution coordinator obtains parallel execution servers from the pool and assigns them to the operation. If necessary, Oracle Database can create additional parallel execution servers for the operation. These parallel execution servers remain with the operation throughout execution. After the statement has been processed completely, the parallel execution servers return to the pool. B:

97 *The parallel execution coordinator examines each operation in a SQL statement's execution plan then determines the way in which the rows operated on by the operation must be divided or redistributed among the parallel execution servers. *After the optimizer determines the execution plan of a statement, the parallel execution coordinator determines the parallel execution method for each operation in the plan. Note: *Oracle Database can process a parallel operation with fewer than the requested number of processes. If all parallel execution servers in the pool are occupied and the maximum number of parallel execution servers has been started, the parallel execution coordinator switches to serial processing. Reference:Oracle Database VLDB and Partitioning Guide11g,How Parallel Execution Works QUESTION 83 You need to upgrade you Oracle Database 10g to 11g. You want to ensure that the same SQL plans that are currently in use in the 10g database are used in the upgraded database initially, but new, better plans are allowed subsequently. Steps to accomplish the task: 1. Set the OPTIMIZER_USE_SQL_BASELINE and OPTIMIZER_CAPTURE_SQL_PLAN_BASELINE to TRUE. 2. Bulk load the SQL Management Base as part of an upgrade using an STS containing the plans captured in Oracle Database 10g. 3. Evolve the plan baseline using the DBMS_SPM.EVOLVE_PLAN_BASELINE procedure. 4. Fix the plan baseline using the DBMS_SPM.ALTER_SQL_PLANBASELINE procedure. 5. Accept new, better plans using the DBMS_SPM.ALTER_SQL_PLAN_BASELINE procedure and manually load them to the existing baseline. 6. Set OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES to FALSE. Identify the required steps. A. 1, 3, 4, 5 B. 1, 6, 3, 4, 5 C. 1, 2, 3, 5 D. 1, 2, 3, 4 E. 1, 6, 3 F. 1 and 2 Correct Answer: F /Reference: * (1)OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES In Oracle Database 11g a new feature called SQL Plan Management (SPM) has been introduced to guarantees any plan changes that do occur lead to better performance. When OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES is set to TRUE (default FALSE) Oracle will automatically capture a SQL plan baseline for every repeatable SQL statement on the system. The execution plan found at parse time will be added to the SQL plan baseline as an accepted plan. * (2)Once you have completed the software upgrade, but before you restart the applications and allow users back on the system, you should populate SQL Plan Management (SPM) with the 10g execution plans you captured before the upgrade. Seeding SPM with the 10g execution plans ensures that the application will continue to use the same execution plans you had before the

98 upgrade.any new execution plans found in Oracle Database 11g will be recorded in the plan history for that statement but they will not be used. When you are ready you can evolve or verify the new plans and only implement those that perform better than the 10g plan. Incorrect: Not (3):DBMS_SPM.EVOLVE_PLAN_BASELINEis not used to evolve new plans.dbms_spm.evolve_sql_plan_baselineshould be used: It is possible to evolve a SQL statement s execution plan using Oracle Enterprise Manager or by running the command-line function DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE. U Note: *SQL plan management (SPM) ensures that runtime performance will never degrade due to the change of an execution plan. To guarantee this, only accepted (trusted) execution plans will be used; any plan will be tracked and evaluated at a later point in time and only accepted as verified if the new plan performs better than an accepted plan. SQL Plan Management has three main components: 1. SQL plan baseline capture: Create SQL plan baselines that represents accepted execution plans for all relevant SQL statements. The SQL plan baselines are stored in a plan history inside the SQL Management Base in the SYSAUX tablespace. 2. SQL plan baseline selection Ensure that only accepted execution plans are used for statements with a SQL plan baseline and track all new execution plans in the history for a statement as unaccepted plan. The plan history consists of accepted and unaccepted plans. An unaccepted plan can be unverified (newly found but not verified) or rejected (verified but not found to performant). 3. SQL plan baseline evolution Evaluate all unverified execution plans for a given statement in the plan history to become either accepted or rejected QUESTION 84 You are administering a database supporting an OLTP workload where the users perform frequent queries for fetching a new rows as possible, involving join operations on recently inserted data. In addition at night, a few DSS queries are also performed. Examine the initialization parameters for the instance: Which two options would you use for the optimizer? A. Set the OPTIMIZER_MODE initialization parameter to FIRST_ROWS_n. B. Add the hint ALL_ROWS in the DOS queries. C. Set the OPTIMIZER_INDEX_CACHING initialization parameter to 0. D. Add a hint INDEX_COMBINE in all DSS queries. E. Set the OPTIMIZER_INDEX_COST_ADJ initialization parameter to 100. Correct Answer: AE

99 /Reference: The last appended rows are more likely to be found quickly withfirst_rows_n. E: Make it not to prioritize index instead if table scan. OPTIMIZER_INDEX_COST_ADJ OPTIMIZER_INDEX_COST_ADJ lets you tune optimizer behavior for access path selection to be more or less index friendly that is, to make the optimizer more or less prone to selecting an index access path over a full table scan. The default for this parameter is 100 percent, at which the optimizer evaluates index access paths at the regular cost. Any other value makes the optimizer evaluate the access path at that percentage of the regular cost. For example, a setting of 50 makes the index access path look half as expensive as normal. QUESTION 85 See the table below: All execution servers are currently available and the sessions use defaults for all parallel settings. In which two cases will statements execute in parallel? A. When parallel hints are used but only if estimated serial execution takes more than 10 seconds. B. When parallelism is defined at the statement level. C. When the degree of parallelism is explicitly defined in the data dictionary for tables and indexes accessed by a query. D. Parallel DDL statements but only if estimated serial DDL execution time is greater than 10 seconds. E. When the degree of parallelism is explicitly defined for tables and indexes but only if estimated serial execution takes more than 10 seconds.

100 Correct Answer: BC /Reference: Incorrect: A, D, E: WhenPARALLEL_MIN_TIME_THRESHOLD is set to AUTO theparallel_min_time_threshold is set to 30, not to 10. See note below. Note: * parallel_min_time_threshold PARALLEL_MIN_TIME_THRESHOLD specifies the minimum execution time a statement should have before the statement is considered for automatic degree of parallelism. By default, this is set to 30 seconds. Automatic degree of parallelism is only enabled if PARALLEL_DEGREE_POLICY is set to AUTO or LIMITED. QUESTION 86 You need to migrate database from oracle Database 10g to 11g. You want the SQL workload to start the 10g plans in the 11g database instance and evolve better plans. Examine the following steps: 1. Capture the pre-oracle Database 11g plans in a SQL Tuning Set (STS) 2. Export the STS from the 10g system. 3. Import the STS into Oracle Database 11g. 4. Set the OPTIMIZER_FEATURES_ENABLE parameter to Run SQL Performance Analyzer for the STS. 6. Set the OPTIMIZER_FEATURES_ENABLE parameter to Rerun the SQL Performance Analyzer for the STS. 8. Set OPTIMIZER_CAPTURE_SQL_PLAN_BASELINE to TRUE. 9. Use DBMS_SPM.EVOLVE_SQL_BASELINE function to evolve the plans. 10. Set the OPTIMIZER_USE_SQL_PLAN_BASELINE to TRUE. Identify the required steps in the correct order. A. 1, 2, 3, 4, 5, 6, 7 B. 4, 8, 10 C. 1, 2, 3, 4, 8, 10 D. 1, 2, 3, 6, 9, 5 E. 1, 2, 3, 5, 9, 10 Correct Answer: C /Reference: Step 1: (1) Step 2: (2) Step 3: (3) Step 4: (4) By setting the parameter OPTIMIZER_FEATURES_ENABLE to the 10g version used before the upgrade, you should be able to revert back to the same execution plans you had prior to the upgrade. Step 5: (8) OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES In Oracle Database 11g a new feature called SQL Plan Management (SPM) has been introduced to guarantees any plan changes that do occur lead to better performance. When OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES is set to TRUE (default FALSE) Oracle will

101 automatically capture a SQL plan baseline for every repeatable SQL statement on the system. The execution plan found at parse time will be added to the SQL plan baseline as an accepted plan. Step 6: (10) OPTIMIZER_USE_SQL_PLAN_BASELINES enables or disables the use of SQL plan baselines stored in SQL Management Base. When enabled, the optimizer looks for a SQL plan baseline for the SQL statement being compiled. If one is found in SQL Management Base, then the optimizer will cost each of the baseline plans and pick one with the lowest cost. QUESTION 87 A database instance is configured in the shared server mode and it supports multiple applications running on a middle tier. These applications connect to the database using different services. You enabled the statistics gathering for the service by using the following command: SQL > EXECUTE DBMS_MONITOR.SERV_MOD_ACT_STAT_ENABLE ( APPS1, NULL, NULL); Which two statements are true regarding statistics gathered for APPS1 service? A. The statistics are gathered for all the modules and actions within the service. B. The statistics are collected at the session level for all sessions connected using the service. C. The statistics are aggregated and stored in the V$SERV_MOD_ACT_STATS view. D. The statistics are gathered for all the modules using the service only when DBMS_APPLICATION_INFO.SET_MODULE is executed to register with the service. E. Statistics gathering is enabled only for the subsequent sessions using the service. F. The statistics are gathered for all the applications using the service only when DBMS_APPLICATION_INFO.SET_ACTION is executed to register with the service. Correct Answer: BC /Reference: --MI DAVA A,B,C-- SERV_MOD_ACT_STAT_ENABLE Procedure This procedure enables statistic gathering for a given combination of Service Name, MODULE and ACTION. Calling this procedure enables statistic gathering for a hierarchical combination of Service name, MODULE name, and ACTION name on all instances for the same database. Statistics are accessible by means of the V$SERV_MOD_ACT_STATS view. Note: *Syntax DBMS_MONITOR.SERV_MOD_ACT_STAT_ENABLE( service_name IN VARCHAR2, module_name IN VARCHAR2, action_name IN VARCHAR2 DEFAULT ALL_ACTIONS); Parameter,Description service_name Name of the service for which statistic aggregation is enabled module_name Name of the MODULE. An additional qualifier for the service. It is a required parameter. action_name Name of the ACTION. An additional qualifier for the Service and MODULE name. Omitting the parameter (or supplying ALL_ACTIONS constant) means enabling aggregation for all Actions for a

102 given Server/Module combination. In this case, statistics are aggregated on the module level. Reference:Oracle Database PL/SQL Packages and Types Reference11g, SERV_MOD_ACT_STAT_ENABLE Procedure QUESTION 88 In which three situations must you collect optimizer statistics manually for database objects in addition to automatic statistics collection? A. When substantial DML activity occurs between the nightly automatic stats gathering maintenance job B. When substantial activity occurs on a partition of the partitioned table. C. When a table is used for bulk loads that add 10% or more to the total size of the table D. When an index is created or dropped for a column E. When the degree of parallelism is explicitly defined for a table Correct Answer: ABC /Reference: -- MI DAVA B,C-- When to Gather Statistics When gathering statistics manually, you not only need to determine how to gather statistics, but also when and how often to gather new statistics. For an application in which tables are being incrementally modified, you may only need to gather new statistics every week or every month. The simplest way to gather statistics in these environment is to use a script or job scheduling tool to regularly run the GATHER_SCHEMA_STATS and GATHER_DATABASE_STATS procedures. The frequency of collection intervals should balance the task of providing accurate statistics for the optimizer against the processing overhead incurred by the statistics collection process. (C)For tables which are being substantially modified in batch operations, such as with bulk loads, statistics should be gathered on those tables as part of the batch operation. The DBMS_STATS procedure should be called as soon as the load operation completes. For partitioned tables, there are often cases in which only a single partition is modified. In those cases, statistics can be gathered only on those partitions rather than gathering statistics for the entire table. However, gathering global statistics for the partitioned table may still be necessary. QUESTION 89 Examine the query and its execution plan:

103 Which two statements are true regarding the execution plan? A. For every row of CUSTOMERS table, the row matching the join predicate from the ORDERS table are returned. B. An outer join returns NULL for the ORDERS table columns along with the CUSTOMERS table rows when it does not find any corresponding rows in the ORDER table. C. The data is aggregated from the ORDERS table before joining to CUSTOMERS. D. The NESTED LOOP OUTER join is performed because the OPTIMZER_MODE parameter is set to ALL_ROWS. Correct Answer: BD /Reference: B:An outer join extends the result of a simple join. An outer join returns all rows that satisfy the join condition and also returns some or all of those rows from one table for which no rows from the other satisfy the join condition. Note: *All_rows attempts to optimize the query to get the very last row as fast as possible.

104 This makes sense in a stored procedure for example where the client does not regain control until the stored procedure completes. You don't care if you have to wait to get the first row if the last row gets back to you twice as fast. In a client server/interactive application you may well care about that. *The optimizer uses nested loop joins to process an outer join in the following circumstances: / It is possible to drive from the outer table to inner table. / Data volume is low enough to make the nested loop method efficient. *First_rows attempts to optimize the query to get the very first row back to the client as fast as possible. This is good for an interactive client server environment where the client runs a query and shows the user the first 10 rows or so and waits for them to page down to get more. QUESTION 90 An application frequently executed similar types of queries that vary only in the usage of literals in the WHERE clause. You plan to use bind variable in place of literal values. The CURSOR_SHARING parameter to set to EXACT. Which two statements are true about the usage of bind variables? A. The number of latch gets in the library cache will be reduced. B. Bind peeking will take place and subsequent execution of queries can have different plans based on the cardinality of the bind value in the column. C. Bind peeking will take place and subsequent execution of queries can have different plans only when the histograms exists on a column used in WHERE clause. D. Bind peeking will not happen and the optimizer will use the same plan for all bind values if no histograms exist on a column use in the WHERE clause. E. Bind peeking will happen and subsequent execution of queries will have the same parent cursor but different child cursors. Correct Answer: AB /Reference: CURSOR_SHARING determines what kind of SQL statements can share the same cursors. EXACT Only allows statements with identical text to share the same cursor. Note: EXACT-This is the default setting. With this value in place, the query is not rewritten to use bind variables. With CURSOR_SHARING=EXACT (the default), every unique SQL statement executed will create a new entry in V$SQL, it will be hard-parsed, and an execution plan will be created just for it. There can be hundreds or thousands of very similar queries in the shared pool that differ only in the literals used in the SQL statement itself. This implies that the database is forced to hard-parse virtually every query, which, in turn, not only consumes a lot of CPU cycles but also leads to decreased scalability. The database just cannot hard-parse hundreds or thousands of SQL statements concurrently the application ends up waiting for the shared pool to become available. One of the major scalability inhibitors in the database is not using bind variables. That was the motivation behind adding CURSOR_SHARING=FORCE.

105 QUESTION 91 Examine the execution plan:

106 Which two are true regarding the execution plan? A. The CUSTOMERS table is hash partitioned. B. The SALES table is hash partitioned. C. The CUSTOMERS table is scanned first and selected partitions from the SALES table are scanned based on the BLOOM Filter created during the scan of the CUSTOMERS table. D. The SALES table is scanned first and selected partitions from the CUSTOMERS table are scanned based on the Bloom Filter created during the scan of the SALES table. E. Both the CUSTOMERS and SALES tables are scanned simultaneously and rows from the CUSTOMERS table are joined to row of the SALES table. F. The CUSTOMERS table is range partitioned. Correct Answer: BC /Reference: B: As per line 14 and 15. C: As per exhibit line 13 is execute before line 15. Incorrect: Not E: As per line 13 and 15 they are not executed simultaneously. QUESTION 92 Which two tasks are performed during the optimization stage of a SQL statement? A. Evaluating the expressions and conditions in the query B. Checking the syntax and analyzing the semantics of the statement C. Separating the clauses of the SQL statement into structures that can be processed D. Inspecting the integrity constraints and optimizing the query based on this metadata E. Gathering the statistics before creating the execution plan for the statement Correct Answer: DE

107 /Reference: Note: *Oracle SQL is parsed before execution, and a hard parse includes these steps: * The parsing process performs two main functions: o Syntax Check: is the statement a valid one.does it make sense given the SQL grammar documented in the SQL Reference Manual. Does it follow all of the rules for SQL. o Semantic Analysis: Going beyond the syntax? is the statement valid in light of the objects in the database (do the tables and columns referenced exist). Do you have access to the objects? are the proper privileges in place? Are there ambiguities in the statement? for example if there are two tables T1 and T2 and both have a column X, the query?select X from T1, T2 where?? is ambiguous, we don?t know which table to get X from. And so on. So, you can think of parsing as basically a two step process, that of a syntax check to check the validity of the statement and that of a semantic check? to ensure the statement can execute properly. Reference:Oracle hard-parse vs. soft parse QUESTION 93 Examine the Exhibit1 to view the structure of an indexes for the EMPLOYEES table. Examine the query: SQL> SELECT * FROM employees WHERE employees_id IN (7876, 7900, 7902); EMPLOYEE_ID is a primary key in the EMPLOYEES table that has rows. Which statement is true regarding the execution of the query? Exhibit:

108 A. The query uses an index skip scan on the EMP_EMP_ID_PK index to fetch the rows. B. The query uses the INLIST ITERATOR operator to iterate over the enumerated value list, and values are evaluated using an index range scan on the EMP_EMP_ID_PK index. C. The query uses the INLIST ITERATOR operator to iterate over the enumerated value list, and values are evaluated using a fast full index scan on the EMP_EMP_ID_PK index. D. The query uses the INLIST ITERATOR operator to iterate over the enumerated value list, and values are evaluated using an index unique scan on the EMP_EMP_ID_PK index. E. The query uses a fast full index scan on the EMP_EMP_ID_PK index fetch the rows. Correct Answer: B /Reference: How the CBO Evaluates IN-List Iterators The IN-list iterator is used when a query contains an IN clause with values. The execution plan is identical to what would result for a statement with an equality clause instead of IN except for one additional step. That extra step occurs when the IN-list iterator feeds the equality clause with unique values from the IN-list. Both of the statements in Example 2-1 and Example 2-1 are equivalent and produce the same

109 plan. Example 2-1 IN-List Iterators Initial Statement SELECT header_id, line_id, revenue_amount FROM so_lines_all WHERE header_id IN (1011,1012,1013); SELECT header_id, line_id, revenue_amount FROM so_lines_all WHERE header_id = 1011 OR header_id = 1012 OR header_id = 1013; Plan SELECT STATEMENT INLIST ITERATOR TABLE ACCESS BY INDEX ROWID SO_LINES_ALL INDEX RANGE SCAN SO_LINES_N1 Reference:Database Performance Tuning Guide and Reference QUESTION 94 You are administering a database supporting a DDS workload in which some tables are updated frequently but not queried often. You have SQL plan baseline for these tables and you do not want the automatic maintenance task to gather statistics for these tables regularly. Which task would you perform to achieve this? A. Set the INCREMENTAL statistic preference FALSE for these tables. B. Set the STALE_PERCENT static preference to a higher value for these tables. C. Set the GRANULARITY statistic preference to AUTO for these tables. D. Set the PUBLISH statistic preference to TRUE for these tables. Correct Answer: B /Reference: With the DBMS_STATS package you can view and modify optimizer statistics gathered for database objects. STALE_PERCENT - This value determines the percentage of rows in a table that have to change before the statistics on that table are deemed stale and should be regathered. The default value is 10%. Reference:OracleDatabase PL/SQL Packages and Types Reference QUESTION 95 Your database has the OLTP_SRV service configured for an OLTP application running on a middle tier. This service is used to connect to the database by using connection pools. The application has three modules. You enabled tracing at the service by executing the following command: SQL exec DBMS_MONITOR.SERV_MOD_ACT_TRACE_ENABLE ( OLTP_SRV ); What is the correct method of consolidating the trace files generated by the procedure?

110 A. Use all trace files as input for the tkprof utility to consolidate the trace files for a module. B. Use one trace file at a time as input for the trcess utility and use tkprof utility to consolidate all the output files for a module. C. Use the trcess utility to consolidate all trace files into a single output file, which can then be processed by the tkprof utility. D. Use the tkprof utility to consolidate the trace files and create an output that can directly be used for diagnostic purposes. Correct Answer: C /Reference: Note: *Oracle provides the trcsess command-line utility that consolidates tracing information based on specific criteria. The SQL Trace facility and TKPROF are two basic performance diagnostic tools that can help you monitor applications running against the Oracle Server. Note:SERV_MOD_ACT_TRACE_ENABLE Procedure Enables SQL tracing for a given combination of Service Name, MODULE and ACTION globally unless an instance_name is specified Reference: OracleDatabase Performance Tuning Guide QUESTION 96 Which statement is true about an automatic SQL task? A. It will attempt to tune the currently running SQL statements that are highly resource intensive. B. It will automatically implement new SQL profiles for the statements that have existing SQL profiles. C. It will attempt to tune all-long-running queries that have existing SQL profiles. D. It will automatically implement SQL profiles if a three-fold benefit can be achieved and automatic profile implementation is enabled. E. It will tune all the top SQL statements from AWR irrespective of the time it takes to complete the task in a maintenance window. Correct Answer: D /Reference: Optionally, implements the SQL profiles provided they meet the criteria of threefold performance improvement The database considers other factors when deciding whether to implement the SQL profile. For example, the database does not implement a profile when the objects referenced in the statement have stale optimizer statistics. SQL profiles that have been implemented automatically show type is AUTO in the DBA_SQL_PROFILES view. If the database uses SQL plan management, and if a SQL plan baseline exists for the SQL statement, then the database adds a new plan baseline when creating the SQL profile. As a result, the optimizer uses the new plan immediately after profile creation. Incorrect: E:Oracle Database automatically runs SQL Tuning Advisor on selected high-load SQL statements from the Automatic Workload Repository (AWR) that qualify as tuning candidates. This task, called Automatic SQL Tuning, runs in the default maintenance windows on a nightly basis. By default, automatic SQL tuning runs for at most one hour.

111 Note: After automatic SQL tuning begins, the database performs the following steps: Oracle Database analyzes statistics in AWR and generates a list of potential SQL statements that are eligible for tuning. These statements include repeating high-load statements that have a significant impact on the database. The database tunes only SQL statements that have an execution plan with a high potential for improvement. The database ignores recursive SQL and statements that have been tuned recently (in the last month), parallel queries, DML, DDL, and SQL statements with performance problems caused by concurrency issues. The database orders the SQL statements that are selected as candidates based on their performance impact. The database calculates the impact by summing the CPU time and the I/O times in AWR for the selected statement in the past week. During the tuning process, the database considers and reports all recommendation types, but it can implement only SQL profiles automatically. Reference: OracleDatabase Performance Tuning Guide,Automatic SQL Tuning QUESTION 97 Examine the exhibit. Which two are true concerning the execution plan? Exhibit: A. No partition-wise join is used

112 B. A full partition-wise join is used C. A partial partition-wise join is used D. The SALES table is composite partitioned Correct Answer: BD /Reference: *The following example shows the execution plan for the full partition-wise join with the sales table range partitioned by time_id, and subpartitioned by hash on cust_id Id Operation Name Pstart Pstop IN-OUT PQ Distrib SELECT STATEMENT 1 PX COORDINATOR 2 PX SEND QC (RANDOM) :TQ10001 P->S QC (RAND) * 3 FILTER PCWC 4 HASH GROUP BY PCWP 5 PX RECEIVE PCWP 6 PX SEND HASH :TQ10000 P->P HASH 7 HASH GROUP BY PCWP 8 PX PARTITION HASH ALL 1 16 PCWC * 9 HASH JOIN PCWP 10 TABLE ACCESS FULL CUSTOMERS 1 16 PCWP 11 PX PARTITION RANGE ITERATOR 8 9 PCWC * 12 TABLE ACCESS FULL SALES PCWP Predicate Information (identified by operation id): filter(count(sys_op_csr(sys_op_msr(count(*)),0))>100) 9 - access("s"."cust_id"="c"."cust_id") 12 - filter("s"."time_id"<=to_date(' :00:00', 'syyyy-mm-dd hh24:mi:ss') AND "S"."TIME_ID">=TO_DATE(' :00:00', 'syyyy-mm-dd hh24:mi:ss')) *Full partition-wise joins can occur if two tables that are co-partitioned on the same key are joined in a query. The tables can be co-partitioned at the partition level, or at the subpartition level, or at a combination of partition and subpartition levels. Reference partitioning is an easy way to guarantee co-partitioning. Full partition-wise joins can be executed in serial and in parallel. Reference: Oracle Database VLDB and Partitioning Guide, Full Partition-Wise Joins: Composite - Single-Level QUESTION 98 You are working on a database that supports an OLTP workload. You see a large number of hard parses occurring and several almost identical SQL statements in the library cache that vary only in the literal values in the WHERE clause conditions. Which two methods can you use to reduce hard parsing? A. Replace literals with bind variables and evolve a baseline for the statement. B. Use the RESULT_CACHE hint in the queries. C. Create baselines for the almost identical SQL statement by manually loading them from the cursor cache. D. Set the CURSOR_SHARING parameter to SIMILAR.

113 Correct Answer: D /Reference: A:We can reduce this Hard parsing by using bindvariables D:SIMILAR Causes statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect either the meaning of the statement or the degree to which the plan is optimized. Note: A hard parse is when your SQL must be re-loaded into the shared pool. A hard parse is worse than a soft parse because of the overhead involved in shared pool RAM allocation and memory management. Once loaded, the SQL must then be completely re-checked for syntax & semantics and an executable generated. Excessive hard parsing can occur when your shared_pool_size is too small (and reentrant SQL is paged out), or when you have non-reusable SQL statements without host variables. See the cursor_sharing parameter for a easy way to make SQL reentrant and remember that you should always use host variables in you SQL so that they can be reentrant. Reference: Oracle Database Reference, CURSOR_SHARING QUESTION 99 You are administering a database that supports an OLTP workload. Automatic optimizer statistics collection is scheduled in the night maintenance window. Some of the tables get updated frequently during day time and you notice a performance degradation for queries using those tables due to stale statistics. Which two options might help to avoid the performance degradation of the queries? A. Set the global statistics preference STALE_PERCENT to 0. B. Use dynamically sampling hint for the queries on frequently updated tables. C. Create histogram for the columns used frequently in the WHERE clause. D. Gather statistics with global statistics preference NO_VALIDATE to TRUE. E. Set the OPTIMZER_USE_PENDING_STATISTICS parameter to TRUE. Correct Answer: BC /Reference: B:Dynamic sampling first became available in Oracle9i Database Release 2. It is the ability of the cost-based optimizer (CBO) to sample the tables a query references during a hard parse, to determine better default statistics for unanalyzed segments, and to verify its guesses. This sampling takes place only at hard parse time and is used to dynamically generate better statistics for the optimizer to use, hence the name dynamic sampling. There are two ways to use dynamic sampling: The OPTIMIZER_DYNAMIC_SAMPLING parameter can be set at the database instance level and can also be overridden at the session level with the ALTER SESSION command. The DYNAMIC_SAMPLING query hint can be added to specific queries. C:A histogram is a collection of information about the distribution of values within a column.in some cases, the distribution of values within a column of a table will affect the optimizer's decision to use an index vs. perform a full-table scan. This scenario occurs when the value with a where clause has a disproportional amount of values, making a full-table scan cheaper than index

114 access. Histograms are also important for determinine the optimal table join order. Incorrect: A: Too much statistics would be gathered. Note: STALE_PERCENT - This value determines the percentage of rows in a table that have to change before the statistics on that table are deemed stale and should be regathered. The default value is 10%. D:In Oracle PL/SQL, the VALIDATE keyword defines the state of a constraint on a column in a table. E:OPTIMZER_USE_PENDING_STATISTICS specifies whether or not the optimizer uses pending statistics when compiling SQL statements. QUESTION 100 Examine the exhibit to view the query and its execution plan. Identify the two correct interpretations that can be made from the execution plan. Exhibit:

115 A. The DEPT table is driving table and the EMP table join is the driven table. B. Rows from the DEPT table are first hashed by the join key into memory and then joined to the EMP table on the join key. C. The EMP table is the driving table and the DEPT table us the driven table. D. The rows from the DEPT table are sorted first by the join key and then hashed into memory. E. Rows from both the tables are sorted by the join key, but only rows from the DEPT table are hashed into memory. Correct Answer: AB /Reference: Note: *A hash join is performed by hashing one data set into memory based on join columns and reading the other one and probing the hash table for matches. The hash join is very low cost when the hash table can be held entirely in memory, with the total cost amounting to very little more than the cost of reading the data sets. The cost rises if the hash table has to be spilled to disk in a onepass sort, and rises considerably for a multipass sort. You should note that hash joins can only be used for equi-joins, but merge joins are more flexible. In general, if you are joining large amounts of data in an equi-join then a hash join is going to be a better bet. *The 'driving' table is the table we will join FROM -- that is JOIN TO other tables. For example, lets say you have the query: select * from emp, dept where emp.deptno = dept.deptno; In this case the driving table might be DEPT, we would fetch rows from DEPT in a full scan and then find the rows in EMP that match. DEPT is the driving table. QUESTION 101 You are administering a database that supports a DSS workload, where in an application a set of queries use the query rewrite on materialized views. You notice that these queries are performing poorly. Which two actions can you make to improve the performance of theses queries? A. Use DBMS_MVIEW.EXPLAIN_REWRITE to analyze whether the queries are rewritten. B. USE DBMS_ADVISOR.QUICK_TUNE to analyze the query rewrite usage of materialized views for the entire workload. C. Create an STS for all the queries and use SQL performance Analyzer to generate recommendations for determining the regressed SQL statements. D. Create an STS for all the queries in the application and use the SQL Tuning Advisor to generate recommendations. E. Create an STS for all the queries in the application and use the SQL Access Advisor to generate a recommendation for optimizing materialized views for maximum query rewrite usage and fast refresh. Correct Answer: BD /Reference: B:

116 *The dbms_advisor package has a procedure called dbms_advisor.quick_tune that allows the DBA to quickly tune a single SQL statement with a single procedure call. This procedure performs all of the stages that are necessary to launch the SQLAccess Advisor, e.g. creating a task, creating and populating a workload, and executing the task. *QUICK_TUNE Procedure This procedure performs an analysis and generates recommendations for a single SQL statement. This provides a shortcut method of all necessary operations to analyze the specified SQL statement. The operation creates a task using the specified task name. The task will be created using a specified Advisor task template. Finally, the task will be executed and the results will be saved in the repository. Note: * DSS -decision support system *In tuning mode, the optimizer performs additional analysis to check whether the execution plan produced under normal mode can be improved further. The output of the query optimizer is not an execution plan, but a series of actions, along with their rationale and expected benefit for producing a significantly superior plan. When running in the tuning mode, the optimizer is referred to as the Automatic Tuning Optimizer. Incorrect: A:DBMS_MVIEW.EXPLAIN_REWRITE This procedure enables you to learn why a query failed to rewrite, or, if it rewrites, which materialized views will be used. Using the results from the procedure, you can take the appropriate action needed to make a query rewrite if at all possible. The query specified in the EXPLAIN_REWRITE statement is never actually executed. QUESTION 102 You are administering a database that supports an OLTP workload in which one of the applications inserts rows in a table until 12 noon every, after which multiple years perform frequent queries on the table. You want the statistics to be more representative of the table population. What must be done to ensure that an optimizer uses the latest statistics of the table? A. Set the STALE_PERCENT preference to 0. B. Set the OPTIMIZER_MODE parameter to ALL_ROWS. C. Set the OPTIMIZER_DYNAMIC_SAMPLING parameter to 0. D. Use the FIRST_ROWS_n hint in the queries. E. Unlock and gather statistics for the table after inserts are done and lock them again. Correct Answer: E /Reference: * For tables that are substantially modified in batch operations, such as with bulk loads, gather statistics on these tables as part of the batch operation. Call the DBMS_STATS procedure as soon as the load operation completes. * Statistics for a table or schema can be locked. After statistics are locked, you can make no modifications to the statistics until the statistics have been unlocked. Locking procedures are useful in a static environment in which you want to guarantee that the statistics never change. The DBMS_STATS package provides two procedures for locking (LOCK_SCHEMA_STATS and LOCK_TABLE_STATS) and two procedures for unlocking statistics (UNLOCK_SCHEMA_STATS andunlock_table_stats). Incorrect:

117 A: STALE_PERCENT cannot be set to 0. *With the DBMS_STATS package you can view and modify optimizer statistics gathered for database objects. STALE_PERCENT - This value determines the percentage of rows in a table that have to change before the statistics on that table are deemed stale and should be regathered. The default value is 10%. B: Optimizer_mode applies to the database, not to a specific table. * Possible values for optimizer_mode = choose/ all_rows/ first_rows/ first_rows[n] Important facts about ALL_ROWS C:Optimizer dynamic sampling refers to the ability of the SQL optimizer to take a sample of rows from a table to calculate missing statistics. Dynamic sampling can be controlled with the OPTIMIZER_DYNAMIC_SAMPLING parameter or the DYNAMIC_SAMPLING hint. level 0 - do not use dynamic sampling D: First_row_n cannot be used in this way. QUESTION 103 Examine the query: The RESULT_CACHE_MODE parameter is set to MANUAL for the database. Which two statements are true about the usage of the result cache? A. The SQL runtime environment checks whether the query result is cached in the result cache; if the result exists, the optimizer fetches the result from it. B. The SQL runtime environment does check for the query result in the result cache because the RESULT_CACHE_MODE parameter is set to MANUAL. C. The SQL runtime environment checks for the query result in the result cache only when the query is executed for the second time. D. If the query result does not exist in the cache and the query is executed, the result is generated as output, and also sorted in the result cache. Correct Answer: AD /Reference: Note: *result_cache_mode: the result cache can be enabled in three ways: via hint, alter session or alter system. Default is MANUAL which means that we need to explicitly request caching via the RESULT_CACHE hint; *As its name suggests, the query result cache is used to store the results of SQL queries for reuse in subsequent executions. By caching the results of queries, Oracle can avoid having to repeat the potentially time-consuming and intensive operations that generated the resultset in the first place (for example, sorting/aggregation, physical I/O, joins etc). The cache results themselves are available across the instance (i.e. for use by sessions other than the one that first executed the query) and are maintained by Oracle in a dedicated area of memory. Unlike our homegrown solutions using associative arrays or global temporary tables, the query result cache is completely transparent to our applications. It is also maintained for consistency automatically, unlike our own caching programs.

118 *RESULT_CACHE_MODE specifies when a ResultCache operator is spliced into a query's execution plan. Values: /MANUAL The ResultCache operator is added only when the query is annotated (that is, hints). /FORCE The ResultCache operator is added to the root of all SELECT statements (provided that it is valid to do so). For the FORCE setting, if the statement contains a NO_RESULT_CACHE hint, then the hint takes precedence over the parameter setting. QUESTION 104 How can you analyze an existing trace file to list the almost resource-intensive statements, aggregation of statistics, and to either exclude recursive call details? A. By using the DBMS_TRACE package B. By using the EXPLAIN PLAN command C. By enabling the SQL_TRACE parameter for the session D. By using the TKPROF utility E. By using the TRCSESS utility Correct Answer: D /Reference: D:You can run the TKPROF program to format the contents of the trace file and place the output into a readable output file. TKPROF can also: *Create a SQL script that stores the statistics in the database *Determine the execution plans of SQL statements TKPROF reports each statement executed with the resources it has consumed, the number of times it was called, and the number of rows which it processed. This information lets you easily locate those statements that are using the greatest resource. With experience or with baselines available, you can assess whether the resources used are reasonable given the work done. Incorrect: A:DBMS_TRACE provides subprograms to start and stop PL/SQL tracing in a session. Oracle collects the trace data as the program executes and writes it to database tables. A typical session involves: Starting PL/SQL tracing in session (DBMS_TRACE.SET_PLSQL_TRACE). Running an application to be traced. Stopping PL/SQL tracing in session (DBMS_TRACE.CLEAR_PLSQL_TRACE). E:The trcsess utility consolidates trace output from selected trace files based on several criteria: Session Id Client Id Service name Action name Module name

119 After trcsess merges the trace information into a single output file, the output file could be processed by TKPROF Reference: OracleDatabase Performance Tuning Guide,Understanding TKPROF QUESTION 105 Which statement is true about the usage of the STAR_TRANSFORMATION hint in a query? A. The optimizer always uses a plan in which the transformation is used. B. The optimizer uses transformation only if the cost is less than a query executing without transformation. C. The optimizer always generates subqueries to transform a query. D. The optimizer always uses bitmap indexes on the primary key column for any dimension table to transform a query. Correct Answer: A /Reference: The STAR_TRANSFORMATION hint makes the optimizer use the best plan in which the transformation has been used. Without the hint, the optimizer could make a cost-based decision to use the best plan generated without the transformation, instead of the best plan for the transformed query. Even if the hint is given, there is no guarantee that the transformation will take place. The optimizer only generates the subqueries if it seems reasonable to do so. If no subqueries are generated, then there is no transformed query, and the best plan for the untransformed query is used, regardless of the hint. Reference: OracleDatabase SQL Language Reference,STAR_TRANSFORMATION Hint QUESTION 106 Examine the Exhibit to view the structure of and indexes for the EMPLOYEES and DEPARTMENTS tables: EXAMINE the SQL statement and its execution plan:

120 Which two statements are correct regarding the execution plan? Exhibit:

121 A. Step 2 is performing nested operation on JOB_ID column of the JOBS table, which is the driven table and the EMPLOYEES table is the driven table. B. In step 2 for every row returned by the JOBS table matching rows from the EMPLOYEES table are accessed. C. Step 1 is performing nested loop operation on the DEPARTMENT_ID column of the DEPARTMENTS table, which is the driven table and results returned by step 2 in the driving resultset. D. The performance of the query can be improved by creating bitmap index on the JOB_ID column of the EMPLOYEES table. E. The performance of the query can be improved by creating bitmapped index on the DEPARTMENT_ID column of the EMPLOYEES table. Correct Answer: BE

122 /Reference: As per exhibit: B, not A, Not C: First isline 5executed, followed by line 4, followed by line 3. Step 2 is line 4. E: The Department_ID column has lower cardinality compared to the JOB_ID column, so it is better suited for a bitmapped index. Note: *Oracle bitmap indexes are very different from standard b-tree indexes. In bitmap structures, a two-dimensional array is created with one column for every row in the table being indexed. Each column represents a distinct value within the bitmapped index. This two-dimensional array represents each value within the index multiplied by the number of rows in the table. At row retrieval time, Oracle decompresses the bitmap into the RAM data buffers so it can be rapidly scanned for matching values. These matching values are delivered to Oracle in the form of a Row-ID list, and these Row-ID values may directly access the required information. *The real benefit of bitmapped indexing occurs when one table includes multiple bitmapped indexes. Each individual column may have low cardinality. The creation of multiple bitmapped indexes provides a very powerful method for rapidly answering difficult SQL queries. *Oracle bitmap indexes are very different from standard b-tree indexes. In bitmap structures, a two-dimensional array is created with one column for every row in the table being indexed. Each column represents a distinct value within the bitmapped index. This two-dimensional array represents each value within the index multiplied by the number of rows in the table. At row retrieval time, Oracle decompresses the bitmap into the RAM data buffers so it can be rapidly scanned for matching values. These matching values are delivered to Oracle in the form of a Row-ID list, and these Row-ID values may directly access the required information. QUESTION 107 Which two statements are true about the use of the DYNAMIC_SAMPLING hint in a query? A. It estimates selectivity better for the filters. B. It is always used for flashback queries that contain the AS OF clause. C. It cannot be used if there is a single-table predicate in the WHERE clause. D. It cannot be used for processing SQL statements in parallel. E. It can compensate for the lack of extended statistics to get accurate cardinality estimates for complex predicate expressions. Correct Answer: DE /Reference: D:For parallel statements, the optimizer automatically decides whether to use dynamic sampling and which level to use. The decision depends on the size of the tables and the complexity of the predicates. The optimizer expects parallel statements to be resource-intensive,so the additional overhead at compile time is worth it to ensure the best plan. The database ignores the For serially processed SQL statements, the dynamic sampling level depends on the value of the OPTIMIZER_DYNAMIC_SAMPLING parameter andis not triggered automatically by the optimizer. Serial statements are typically shortrunning, so that any overhead at compile timecould have a huge impact on their performance. the value is honored.

123 Reference: OracleDatabase Administrator's Guide,About Oracle Database Resource Manager QUESTION 108 Your database supports a workload consisting of three categories of SQL statements: - Statements that should execute in less than one minute - Statement that may execute for up to 15 minutes - Statements that may be executed for more than 15 minutes You set PARALLEL_DEGREE_POLICY to Auto. You plan to prioritize queued statements by using the Database Resource manager. Which two are true about parallelism prioritization by a consumer group? A. PARALLEL_TARGET_PERCENTAGE is used to prioritize a consumer group s use of the overall PARALLEL_SERVER_TARGET. B. Queuing is done for a consumer group exceeding its percentage, even if the number of busy PX servers in the instance has not reached PARALLEL_SERVERS_TARGET. C. PARALLEL_TARGET_PERCENTAGE us used to prioritize a consumer group s use of the overall SPAN CLASS = OracleCode > PARALLEL_MAX_SERVERS. D. Having separate queues for consumer groups requires the use of management attributes (MGMT_P1, MGMT_P2 etc... ) E. Separate queue timeout using PARALLEL_QUEUE_TIMEOUT require the use of management attributes (MGMT_P1, MGMT_P2 etc... groups) Correct Answer: AD /Reference: A:Parallel Target Percentage It is possible for a single consumer group to launch enough parallel statements to use all the available parallel servers. If this happens, when a high-priority parallel statement from a different consumer group is run, no parallel servers are available to allocate to this group. You can avoid such a scenario by limiting the number of parallel servers that can be used by a particular consumer group. Use the PARALLEL_TARGET_PERCENTAGE directive attribute to specify the maximum percentage of the parallel server pool that a particular consumer group can use. The number of parallel servers used by a particular consumer group is counted as the sum of the parallel servers used by all sessions in that consumer group. Incorrect: Not B:PARALLEL_SERVERS_TARGET specifies the number of parallel server processes allowed to run parallel statements before statement queuing will be used. When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle will queue SQL statements that require parallel execution, if the necessary parallel server processes are not available. Statement queuing will begin once the number of parallel server processes active on the system is equal to or greater than PARALLEL_SERVER_TARGET. Not C: Would be true if we replaceparallel_max_serverswithparallel_server_target. Not E:The PARALLEL_QUEUE_TIMEOUT directive attribute enables you to specify the maximum time, in seconds, that a parallel statement can wait in the parallel statement queue before it is timed out. The PARALLEL_QUEUE_TIMEOUT attribute can be set for each consumer group. This attribute is applicable even if you do not specify other management attributes (mgmt_p1, mgmt_p2, and so on) in your resource plan. Note:

124 *PARALLEL_DEGREE_POLICY AUTO Enables automatic degree of parallelism, statement queuing, and in-memory parallel execution. *The PARALLEL_TARGET_PERCENTAGE attribute enables you to specify when parallel statements from a consumer group can be queued. Oracle Database maintains a separate parallel statement queue for each consumer group. *PARALLEL_SERVERS_TARGET specifies the number of parallel server processes allowed to run parallel statements before statement queuing will be used. When the parameter PARALLEL_DEGREE_POLICY is set to AUTO, Oracle will queue SQL statements that require parallel execution, if the necessary parallel server processes are not available. Statement queuing will begin once the number of parallel server processes active on the system is equal to or greater than PARALLEL_SERVER_TARGET. By default, PARALLEL_SERVER_TARGET is set lower than the maximum number of parallel server processes allowed on the system (PARALLEL_MAX_SERVERS) to ensure each parallel statement will get all of the parallel server resources required and to prevent overloading the system with parallel server processes. Note that all serial (non-parallel) statements will execute immediately even if statement queuing has been activated. *Oracle Database Resource Manager (the Resource Manager) enables you to optimize resource allocation among the many concurrent database sessions. The elements of the Resource Manager are: /Resource consumer groupa group of sessions that are grouped together based on resource requirements. The Resource Manager allocates resources to resource consumer groups, not to individual sessions. /Resource plana container for directives that specify how resources are allocated to resource consumer groups. You specify how the database allocates resources by activating a specific resource plan. /Resource plan directiveassociates a resource consumer group with a particular plan and specifies how resources are to be allocated to that resource consumer group. QUESTION 109 Examine the Exhibit. Given two sets of parallel execution processes, SS1 and SS2, which is true? Exhibit:

125

126 A. Each process SS1reads some of the rows from the CUSTOMERS table and sends all the rows it reads to each process in SS2. B. Each process in SS1 reads all the rows from the CUSTOMERS table and distributes the rows evenly among the processes in SS2. C. Each process in SS1 reads some of the rows from the SALES table and sends all the rows it reads to each process in SS2. D. Each process in SS1 reads all the rows from the SALES table and distributes the rows evenly among the processes in SS2. E. Each process in SS1 reads some of the rows from the SALES table and distributes the rows evenly among the processes in SS2. F. Each process in the SS1 reads some of the rows from the CUSTOMERS table and distributes the rows evenly among the processes in SS2. Correct Answer: D /Reference: Note: * The execution starts with line 16 (accessing the SALES table), followed by line 15. * PX BLOCKITERATOR The PX BLOCK ITERATOR row source represents the splitting up of the table EMP2 into pieces so as to divide the scan workload between the parallel scan slaves. The PX SEND and PX RECEIVE row sources represent the pipe that connects the two slave sets as rows flow up from the parallel scan, get repartitioned through the HASHtable queue, and then read by and aggregated on the top slave set. QUESTION 110 See the code fragment You receive the following error message: ORA-12827: insufficient parallel query slaves available Which three parameter settings could you change to avoid this error? A. Decrease the value of PARALLEL_MIN_PERCENT B. Increase the value of PARALLEL_MAX_SERVERS C. Increase the value of PARALLEL_MIN_SERVERS

127 D. Reduce the value of PARALLEL_MIN_TIME_THRESHOLF E. Increase the value of PARALLEL_DEGREE_LIMIT F. Set the PARALLEL_DEGREE_POLICY = AUTO G. Set the PARALLEL_DEGREE_POLICY = LIMITED Correct Answer: ABG /Reference: A:ORA-12827: insufficient parallel query slaves available Cause:PARALLEL_MIN_PERCENT parameter was specified and fewer than minimum slaves were acquired Action:either re-execute query with lower PARALLEL_MIN_PERCENT or wait until some running queries are completed, thus freeing up slaves B:Your query doesn't run because you've told Oracle not to run it unless at least 5% of the parallel execution processes are available for your query.set PARALLEL_MIN_PERCENT=0 or increase the number of parallel execution processes by increasing the PARALLEL_MAX_SERVERS parameter. G:PARALLEL_DEGREE_POLICY PARALLEL_DEGREE_POLICY specifies whether or not automatic degree of Parallelism, statement queuing, and in-memory parallel execution will be enabled. LIMITED Enables automatic degree of parallelism for some statements but statement queuing and inmemory Parallel Execution are disabled. Automatic degree of parallelism is only applied to those statements that access tables or indexes decorated explicitly with the PARALLEL clause. Tables and indexes that have a degree of parallelism specified will use that degree of parallelism. Note: PARALLEL_MIN_PERCENT operates in conjunction with PARALLEL_MAX_SERVERS and PARALLEL_MIN_SERVERS. It lets you specify the minimum percentage of parallel execution processes (of the value of PARALLEL_MAX_SERVERS) required for parallel execution. Setting this parameter ensures that parallel operations will not execute sequentially unless adequate resources are available. The default value of 0 means that no minimum percentage of processes has been set. Consider the following settings: PARALLEL_MIN_PERCENT = 50 PARALLEL_MIN_SERVERS = 5 PARALLEL_MAX_SERVERS = 10 If 8 of the 10 parallel execution processes are busy, only 2 processes are available. If you then request a query with a degree of parallelism of 8, the minimum 50% will not be met. You can use this parameter in conjunction with PARALLEL_ADAPTIVE_MULTI_USER. In a multiuser environment, an individual user or application can set PARALLEL_MIN_PERCENT to a minimum value until sufficient resources are available on the system and an acceptable degree of parallelism is returned. QUESTION 111 Examine the parallelism parameters for your instance:

128 Examine the Exhibit to view the query and its explain plan output. All sessions use default parallelism settings. What two steps could you take to make the query execute in parallel? Exhibit:

129 A. Add a parallel hint. B. Decrease the value of PARALLEL_MIN_TIMETHRESHOLD. C. Increase the value of PARALLEL_MIN_SERVERS. D. Increase the value of PARALLEL_MAX_SERVERS. E. Decrease the value of PARALLEL_MIN_PERCENT. Correct Answer: AB /Reference: A:You can rely on hints to set the degree of parallelism, but these can be hard to set correctly.

130 B: Decision tree for query parallelization QUESTION 112 Examine the following command:

131 Which query transformation technique is used by the optimizer in this case? A. View merging B. Filter push-down C. Predicate pushing D. Predicate move-around Correct Answer: C /Reference: In predicate pushing, the optimizer "pushes" the relevant predicates from the containing query block into the view query block. For views that are not merged, this technique improves the subplan of the unmerged view because the database can use the pushed-in predicates to access indexes or to use as filters. For example, suppose you create a view that references two employee tables. The view is defined with a compound query that uses the UNION set operator, as follows: CREATE VIEW all_employees_vw AS ( SELECT employee_id, last_name, job_id, commission_pct, department_id FROM employees ) UNION ( SELECT employee_id, last_name, job_id, commission_pct, department_id FROM contract_workers ); You then query the view as follows: SELECT last_name FROM all_employees_vw WHERE department_id = 50; Because the view is a compound query, the optimizer cannot merge the view's query into the accessing query block. Instead, the optimizer can transform the accessing statement by pushing its predicate, the WHERE clause condition department_id=50, into the view's compound query. The equivalent transformed query is as follows: SELECT last_name FROM ( SELECT employee_id, last_name, job_id, commission_pct, department_id FROM employees WHERE department_id=50 UNION SELECT employee_id, last_name, job_id, commission_pct, department_id FROM contract_workers WHERE department_id=50 );

132 Reference: OracleDatabase Performance Tuning Guide,Predicate Pushing QUESTION 113 You identified some DSS queries that perform expensive join and aggregation operations. The queries access historical data from noncurrent partition of the fact tables. What three actions could you perform to improve the response time of the queries without modifying the SQL statements? A. Set the QUERY_REWRITE_ENABLED to TRUE at the session level. B. Create an STS for the statements, run SQL Tuning Advisor for the STS, and implement any generated recommendations for materialized views. C. Set QUERY_REWRITE_ENABLED to TRUE at the instance level. D. Create an STS for the statements, run SQL Access Advisor for the STS, and implement any generated recommendations for materialized views. E. Set QUERY_REWRITE_INTEGRITY to ENFORCED at the instance level. Correct Answer: BCD /Reference: A:*QUERY_REWRITE_ENABLED allows you to enable or disable query rewriting globally for the database. Values: false Oracle does not use rewrite. true Oracle costs the query with rewrite and without rewrite and chooses the method with the lower cost. force Oracle always uses rewrite and does not evaluate the cost before doing so. Use force when you know that the query will always benefit from rewrite and when reduction in compile time is important. To take advantage of query rewrite for a particular materialized view, you must enable query rewrite for that materialized view, and you must enable cost-based optimization. C:You can use SQL Tuning Advisor to tune one or more SQL statements D:Using the SQL Access Advisor Wizard or API, you can do the following: Note: * STS SQL tuning set. *A SQL Tuning Set is a database object that includes one or more SQL statements and their execution statistics and execution context. You can use the set as an input source for various advisors, such as SQL Tuning Advisor, SQL Access Advisor, and SQL Performance Analyzer. Incorrect: E: QUERY_REWRITE_INTEGRITY determines the degree to which Oracle must enforce query rewriting. At the safest level, Oracle does not use query rewrite transformations that rely on unenforced relationships. Values:

133 enforced Oracle enforces and guarantees consistency and integrity. trusted Oracle allows rewrites using relationships that have been declared, but that are not enforced by Oracle. stale_tolerated Oracle allows rewrites using unenforced relationships. Materialized views are eligible for rewrite even if they are known to be inconsistent with the underlying detail data QUESTION 114 Identify two situations in which full table scans will be faster than index range scans. A. A query with a highly selective filter fetching less than 5 percent of the rows from a table. B. A highly selective query on a table having high clustering factor for an index. C. A query fetching less number of blocks than value specified by DB_FILE_MULTIBLOCK_READ_COUNT. D. A query executing in parallel on a partitioned table with partitioned indexes. E. A query on a table with sparsely populated table blocks. Correct Answer: CD /Reference: D:DB_FILE_MULTIBLOCK_READ_COUNT is one of the parameters you can use to minimize I/O during table scans. It specifies the maximum number of blocks read in one I/O operation during a sequential scan. The total number of I/Os needed to perform a full table scan depends on such factors as the size of the table, the multiblock read count, and whether parallel execution is being utilized for the operation. Online transaction processing (OLTP) and batch environments typically have values in the range of 4 to 16 for this parameter. DSS and data warehouse environments tend to benefit most from maximizing the value of this parameter. The optimizer is more likely to choose a full table scan over an index if the value of this parameter is high. Note: *See 6) and 7) below. The oracle optimizer choose the best plan and execute the query according the plan. It is common to hear that my table has indexes but why oracle does not use indexes rather it is using full table scan. There are several reasons behind choosing optimizer full table scans. 1)The table has no indexes within it. 2)Table has indexes but they are not appropriate to queries. For example in the table there is normal B-tree indexes but in the query the column used in the WHERE clause contains function. 3)Query access large amount of data. The table has indexes but query against it select almost all of the rows. In that case optimizer might choose to full access of table. 4)Index creation order may not appropriate. You have composite indexes on a table but in the where clause the leading column inside indexes are not used rather trailing columns are used. 5)The table is skewed. For example column gender contains value 'M' 10,000 times but value 'F' only 10 times.6)the table is small. If a table can read in a single I/O call, then a full table scan might be cheaper than an index range scan. Single I/O call is defined by DB_FILE_MULTIBLOCK_READ_COUNT parameter and value defined by blocks.check it by,sql> show parameter DB_FILE_MULTIBLOCK_READ_COUNTNAME TYPE VALUE db_file_multiblock_read_count integer 16 7)High degree of parallelism. High degree of parallelism skews the optimizer toward full table

134 scans. 8)In the query if there is no filtering then full table scan is the choice. *If an index has poor cardinality (ie. more than 4% rows with the same index key) then it will perform poorly. It will usually be faster to perform a full table scan. eg. Table SALES has an index on the column PAYMENT_METHOD which can contain values such as COD, CREDIT, CHEQUE, CASH. The statement SELECT * FROM sales WHERE payment_method = 'CASH' will probably perform so badly that you are better off without the index. *Oracle uses the full table scan as it assumes that it will have to read a certain part of the table. Reference: OracleDatabase Reference,DB_FILE_MULTIBLOCK_READ_COUNT QUESTION 115 You are administering a database, where an application frequently executes identical SQL statements with the same syntax. How will you optimize the query results without retrieving data blocks from the storage? A. By setting the CURSOR_SHARING parameter to FORCE. B. By using the bind variables and setting the CURSOR_SHARING parameter to EXACT. C. By using the CACHE hint to pin the queries in the library cache D. By ensuring that RESULT_CACHE_MODE parameter is set to MANUAL and using the RESULT_CACHE hint in the queries. E. By creating a SQL plan baseline for the identical statements. Correct Answer: D /Reference: As its name suggests, the query result cache is used to store the results of SQL queries for re-use in subsequent executions. By caching the results of queries, Oracle can avoid having to repeat the potentially time-consuming and intensive operations that generated the resultset in the first place (for example, sorting/aggregation, physical I/O, joins etc). The cache results themselves are available across the instance (i.e. for use by sessions other than the one that first executed the query) and are maintained by Oracle in a dedicated area of memory. Unlike our homegrown solutions using associative arrays or global temporary tables, the query result cache is completely transparent to our applications. It is also maintained for consistency automatically, unlike our own caching programs. Note: RESULT_CACHE_MODE specifies when a ResultCache operator is spliced into a query's execution plan. Values: MANUAL The ResultCache operator is added only when the query is annotated (that is, hints). FORCE The ResultCache operator is added to the root of all SELECT statements (provided that it is valid to do so).

135 For the FORCE setting, if the statement contains a NO_RESULT_CACHE hint, then the hint takes precedence over the parameter setting. Incorrect: A, B:CURSOR_SHARING determines what kind of SQL statements can share the same cursors. Values: FORCE Forces statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect the meaning of the statement. SIMILAR Causes statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect either the meaning of the statement or the degree to which the plan is optimized. EXACT Only allows statements with identical text to share the same cursor. C:The Oracle library cache is a component of the System Global Area (SGA) shared pool. Similarly to other Oracle cache structures, the point of the library cache is to reduce work and therefore to improve performance by caching the result of parsing and optimizing SQL or PL/SQL so that subsequent executions of the same SQL or PL/SQL require fewer preparatory steps to deliver a query result. QUESTION 116 Which three options are true about MVIEWs? A. The defining query of an MVIEWs may be based on a populated table. B. Queries that are rewritten to an MVIEW will never obtain results from the result cache. C. All MVIEWS may be configured to support refresh on demand. D. The defining query of an MVIEW may be based on non_partitioned table. E. All MVIEWs may be configured to support refresh on commit Correct Answer: ABC /Reference: A:The defining query of a materialized view can select from tables, views, or materialized views owned by the user SYS, but you cannot enable QUERY REWRITE on such a materialized view. B:You cannot specify the following CREATE MATERIALIZED VIEW clauses: CACHE or NOCACHE, CLUSTER, or ON PREBUILT TABLE. C:Specify ON DEMAND to indicate that the materialized view will be refreshed on demand by calling one of the three DBMS_MVIEW refresh procedures. If you omit both ON COMMIT and ON DEMAND, ON DEMAND is the default. Incorrect: E:Materialized views can only refresh ON COMMIT in certain situations. The materialized view cannot contain object types or Oracle-supplied types. The base tables will never have any distributed transactions applied to them.

136 Note: *Oracle uses materialized views (also known as snapshots in prior releases) to replicate data to non-master sites in a replication environment and to cache expensive queries in a data warehouse environment. *A materialized view is a replica of a target master from a single point in time. The master can be either a master table at a master site or a master materialized view at a materialized view site. Whereas in multimaster replication tables are continuously updated by other master sites, materialized views are updated from one or more masters through individual batch updates, known as a refreshes, from a single master site or master materialized view site. QUESTION 117 Partial details of an execution plan. Which statement correctly describes the BITMAP AND operation? A. It produces a bitmap, representing dimension table rows from all dimension tables that join with qualified fact table rows. B. It produces a concentration of the bitmaps for all dimension tables. C. It produces a bitmap, representing fact table rows that do not join with qualified dimension table rows from all dimension tables. D. It produces a bitmap, representing fact table rows that join with qualified dimension table rows from all dimension tables. Correct Answer: D

137 /Reference: Example: Additional set operations will be done for the customer dimension and the product dimension. At this point in the star query processing, there are threebitmaps. Each bitmap corresponds to a separate dimension table, and each bitmap represents the set of rows of the fact table that satisfy that individual dimension's constraints. These three bitmaps are combined into a single bitmap using the bitmap AND operation. This final bitmap represents the set of rows in the fact table that satisfy all of the constraints on the dimension table. Reference: OracleDatabase Data Warehousing Guide,Star Transformation with a Bitmap Index QUESTION 118 Which two statements are true about index full scans? A. An index fast full scan multi block I/O to read the index structure in its entirely. B. Index nodes are not retrieved in the index order, and there fore the nodes are not in sequence. C. An index fast full scan reads the index block by block. D. An index fast full scan reads the whole index from the lowest value to the higher value. Correct Answer: AB /Reference: A:To speed table and index block access, Oracle uses the db_file_multiblock_read_count parameter (which defaults to 8) to aid in getting full-table scan and full-index scan data blocks into the data buffer cache as fast as possible. B:The index nodes are not retrieved in index order, the rows will not be sequenced. Note: there are some requirements for Oracle to invoke the fast full-index scan. Reference:index fast full scan tips QUESTION 119 An application supplied by a new vendor is being deployed and the SQL statements have plan baselines provided by the supplier. The plans have been loaded from a SQL tuning set. You require the optimizer to use these baselines, but allow better plans to used, should any be created. Which two tasks would you perform to achieve this? A. Set the OPTIMIZER_USE_SQL_PLAN_BASELINES initialization parameter to TRUE. B. Set the OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES initialization parameter to TRUE. C. Use the DBMS_SPM.ALTER_SQL_PLAN_BASELINE function to fix the plans. D. Use the DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE function to fix the new plans. E. Use the DBMS_SPM.ALTER_SQL_BASELINE function to accept new plans. Correct Answer: AD /Reference: A:OPTIMIZER_USE_SQL_PLAN_BASELINES enables or disables the use of SQL

138 plan baselines stored in SQL Management Base. When enabled, the optimizer looks for a SQL plan baseline for the SQL statement being compiled. If one is found in SQL Management B ase, then the optimizer will cost each of the baseline plans and pick one with the lowest cost. D:EVOLVE_SQL_PLAN_BASELINE Function This function evolves SQL plan baselines associated with one or more SQL statements. A SQL plan baseline is evolved when one or more of its non-accepted plans is changed to an accepted plan or plans. If interrogated by the user (parameter verify = 'YES'), the execution performance of each non-accepted plan is compared against the performance of a plan chosen from the associated SQL plan baseline. If the non-accepted plan performance is found to be better than SQL plan baseline performance, the non-accepted plan is changed to an accepted plan provided such action is permitted by the user (parameter commit = 'YES'). Incorrect: B:OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES enables or disables the automatic recognition of repeatable SQL statements, as well as the generation of SQL plan baselines for such statements. C:ALTER_SQL_PLAN_BASELINE Function This function changes an attribute of a single plan or all plans associated with a SQL statement using the attribute name/value format. QUESTION 120 You recently gathered statistics for a table by using the following commands: You noticed that the performance of queries has degraded after gathering statistics. You want to use the old statistics. The optimizer statistics retention period is default. What must you do to use the old statistics? A. Use the flashback to bring back the statistics to the desired time. B. Restore statistics from statistics history up to the desired time. C. Delete all the statistics collected after the desired time. D. Set OPTIMIZER_USE_PENDING_STATISTICS to TRUE. Correct Answer: B /Reference: Whenever statistics in dictionary are modified, old versions of statistics are saved automatically for future restoration. Statistics can be restored using RESTORE procedures of DBMS_STATS package. These procedures use a time stamp as an argument and restore statistics as of that time stamp. This is useful in case newly collected statistics leads to some suboptimal execution plans and the administrator wants to revert to the previous set of statistics. Reference:Oracle Database Performance Tuning Guide,Restoring Previous Versions of Statistics QUESTION 121 View the exhibit and examine the plans in the SQL baseline for a given statement. Which interpretation is correct?

139 Exhibit:

140

141 A. A new plan cannot be evolved because SYS_SQL_bbedc41f554c408 is accepted. B. Plan SYS_SQL_PLAN_bbdc741f554c408 will always be used by the optimizer for the query. C. A new plan must be evolved using the DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE function before it can be used. D. Plan SYS_SQL_bbedc741a57b5fc2 can be used by the optimizer if the cost of the query is less than plan SYS_SQL_PLAN_bbedc741f554c408. E. Plan SYS_SQL_PLAN_bbedc741f554c408 will not be used until it is fixed by using the DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE function. Correct Answer: C /Reference: Note: *Evolving a SQL plan baseline is the process by which the optimizer determines if non-accepted plans in the baseline should be accepted. As mentioned previously, manually loaded plans are automatically marked as accepted, so manual loading forces the evolving process. When plans are loaded automatically, the baselines are evolved using the EVOLVE_SQL_PLAN_BASELINE function, which returns a CLOB reporting its results. SET LONG SELECT DBMS_SPM.evolve_sql_plan_baseline(sql_handle => 'SYS_SQL_7b76323ad90440b9') FROM dual; *Manual plan loading can be used in conjunction with, or as an alternative to automatic plan capture. The load operations are performed using the DBMS_SPM package, which allows SQL plan baselines to be loaded from SQL tuning sets or from specific SQL statements in the cursor cache. Manually loaded statements are flagged as accepted by default. If a SQL plan baseline is present for a SQL statement, the plan is added to the baseline, otherwise a new baseline is created. *fixed (YES/NO) : If YES, the SQL plan baseline will not evolve over time. Fixed plans are used in preference to non-fixed plans. QUESTION 122 You want to run SQL Tuning Advisor statements that are not captured by ADDM, AWR, and are not in the library cache. What is the prerequisite? A. Enable SQL plan management B. Create a SQL plan baseline for each query C. Create a SQL Tuning Set (STS) containing the SQL statements D. Gather statistics for objects used in the application Correct Answer: C /Reference: You can use an STS as input to SQL Tuning Advisor, which performs automatic tuning of the SQL statements based on other user-specified input parameters. Note: A SQL tuning set (STS) is a database object that includes one or more SQL statements along with

142 their execution statistics and execution context, and could include a user priority ranking. You can load SQL statements into a SQL tuning set from different SQL sources, such as AWR, the shared SQL area, or customized SQL provided by the user. An STS includes: A set of SQL statements Associated execution context, such as user schema, application module name and action, list of bind values, and the cursor compilation environment Associated basic execution statistics, such as elapsed time, CPU time, buffer gets, disk reads, rows processed, cursor fetches, the number of executions, the number of complete executions, optimizer cost, and the command type Associated execution plans and row source statistics for each SQL statement (optional). Reference:OracleDatabase Performance Tuning Guide,Managing SQL Tuning Sets QUESTION 123 While tuning a SQL statement, the SQL Tuning Advisor finds an existing SQL profile for a statement that has stale statistics. Automatic optimizer statistics is enabled for the database. What does the optimizer do in this situation? A. Updates the existing SQL profiles for which the statistics are stale. B. Makes the statistics information available to GATHER_DATABASE_STATS_JOB_PROC C. Starts the statistics collection process by running GATHER_STATS_JOB D. Writes a warning message in the alert log file Correct Answer: B /Reference: Automatic optimizer statistics collection calls the DBMS_STATS.GATHER_DATABASE_STATS_JOB_PROC procedure. This internal procedure operates similarly to the DBMS_STATS.GATHER_DATABASE_STATS procedure using the GATHER AUTO option. The main difference is that GATHER_DATABASE_STATS_JOB_PROCprioritizes database objects that require statistics, so that objects that most need updated statistics are processed first, before the maintenance window closes. Note: *The optimizer relies on object statistics to generate execution plans. If these statistics are stale or missing, then the optimizer does not have the necessary information it needs and can generate poor execution plans. The Automatic Tuning Optimizer checks each query object for missing or stale statistics, and produces two types of output: /Recommendations to gather relevant statistics for objects with stale or no statistics Because optimizer statistics are automatically collected and refreshed, this problem occurs only when automatic optimizer statistics collection is disabled. See "Managing Automatic Optimizer Statistics Collection". /Auxiliary statistics for objects with no statistics, and statistic adjustment factor for objects with stale statistics The database stores this auxiliary information in an object called a SQL profile. *Oracle recommends that you enable automatic optimizer statistics collection. In this case, the

143 database automatically collects optimizer statistics for tables with absent or stale statistics. If fresh statistics are required for a table, then the database collects them both for the table and associated indexes. Automatic collection eliminates many manual tasks associated with managing the optimizer. It also significantly reduces the risks of generating poor execution plans because of missing or stale statistics. Automatic optimizer statistics collection calls the DBMS_STATS.GATHER_DATABASE_STATS_JOB_PROC procedure. This internal procedure operates similarly to the DBMS_STATS.GATHER_DATABASE_STATS procedure using the GATHER AUTO option. The main difference is that GATHER_DATABASE_STATS_JOB_PROC prioritizes database objects that require statistics,so that objects that most need updated statistics are processed first, before the maintenance window closes. Reference: OracleDatabase Performance Tuning Guide,Managing Automatic Optimizer Statistics Collection QUESTION 124 Refer to the Exhibit. Execution plan:

144 What must be the correct order of steps that the optimizer executes based on the ID column the execution plan? Exhibit: A. 3, 5, 4, 6, 7 B. 3, 5, 4, 7, 6 C. 3, 4, 5, 7, 6 D. 4, 5, 3, 7, 6 Correct Answer: D /Reference: QUESTION 125 Examine the Exhibit.

145 Which two statements are true about the bloom filter in the execution plan? Exhibit: