optimization process (see Optimization process, CBO) RBO, 25 Cursor cache, 41, 42 child, 42 parent, 42

Transcription

1 Index A Access methods bitmap index access CONVERSION COUNT example, 251 INDEX COMBINE, INLIST, 252 manipulation operations, 249 operations, 248, physical structure, 247 restricted ROWIDs, 248 B-tree (see B-tree index access) cluster access methods, operations, 258 full table scans operations, segment full scan, 252 table access sample, 253 ROWIDs (see ROWIDs) TABLE and XMLTABLE CAST MULTISET example, 257 DBMS_XPLAN.display example, 257 nested table, table functions, 255 usage, 254 Adaptive Cursor Sharing, 11gR1, 81 Adaptive execution plans, 81, Advanced tuning techniques INDEX FAST FULL SCAN, INDEX JOIN, JPPD transformation, 519 multi-column indexes, 511, 513 outer-join-to-inner transformation calling code, data dictionary query, 517 PUSH_PRED hint, 518, suboptimal plan, data dictionary view, 516 ROWID ranges, application-coded parallel execution, star transformation, American National Standards Institute (ANSI), 16, 21 ANSI. See American National Standards Institute (ANSI) Anti-joins null-aware, standard, 280 Array interface bind variable, 7 BULK COLLECT syntax, 8 DBAs, 7 DELETE and MERGE, 7 8 DML, 9 Auto DOP. See Automatic degree of parallelism (auto DOP) Automatic degree of parallelism (auto DOP), 29 Automatic Segment Space Management (ASSM), 412, 424 Automatic Workload Repository (AWR), 6 AWR. See Automatic Workload Repository (AWR) B Bitmap join indexes, Block-range granules, 153 B-tree index access AND_EQUAL, 247 INDEX FAST FULL SCAN, INDEX FULL SCAN descending, 240 MIN/MAX optimization, 239 operation, 239 simplified view, INDEX JOIN complex example, 246 HR example schema, 245 manual transformation, 245 INDEX RANGE SCAN descending, MIN/MAX optimization,

2 index B-tree index access (cont.) INDEX SAMPLE FAST FULL SCAN, 244 INDEX SKIP SCAN descending variant, 242 operation, 242 INDEX UNIQUE SCAN, 243 methods, 237 Bushy join ANSI join, 497 execution plan, 497 heuristic transformation, 499 Oracle performance, 496 C Caching effects description, 391 index clustering with multi-column index, 394 index clustering with single-column index, logical I/O operations, 395 CARDINALITY and OPT_ESTIMATE hints CBO, 490 execution plan, 491 INDEX SCAN, 495 NESTED LOOPS, row source, 491 SH.COUNTRIES, 492 Cardinality errors bad physical design, 400 caching effects (see Caching effects) column correlation, contention, 401 Daft data types, description, 387 functions, 390 missing information, stale statistics, 390 statistics feedback and DBMS_STATS.SEED_COL_USAGE features, transitive closure, unsupported transformations, Cardinality feedback, 81 Cartesian joins, 272 CBO. See Cost-based optimizer (CBO) Column correlation, Column projection, Column statistics CBO calculations, 194 Columns with NUM_DISTINCT=1, , data dictionary, 574 data fabrication, 542 DBMS_STATS.UPGRADE_STAT_TABLE, 575 DML, 575 extended statistics for expression, 203 multi-column, HIGH_VALUE and LOW_VALUE, 546 histograms ALL_TAB_COLS, data, 198 faking, 197 gathering procedures, 193 manual creation, 197 missing histogram, 195 SREC parameter, 196 TRANSACTION_AMOUNT, JOB_DESCRIPTION, , 541 METHOD_OPT, 541 parameters, PAYGRADE and PAYMENT_DATE correlation, 537 PAYMENT_DATE, 537 production systems, 527 SAMPLE_PAYMENTS, 537, 541 selection and execution plan, 194 simple cardinality and bytes calculation, 193 SQL, 536, 573 SYS_OP_COMBINED_HASH function, 536 time-based columns, TSTATS_AJAX, 573 TSTATS.AMEND_TIME_BASED_STATISTICS, 537 virtual and hidden columns CBO, data dictionary views, 204 exporting extended statistics, queries, 201 unhidden virtual columns, 198 Columns with NUM_DISTINCT=1 and density, 534 and range predicates, 535 CBO, 530 DBMS_STATS.COPY_TABLE_STATS, 533 HIGH_VALUE and LOW_VALUE, 529 NULL, 529 PAYMENTS, 533 SPECIAL_FLAG, 529 TSTATS.ADJUST_COLUMN_STATS, 533 Cost-based optimizer (CBO) CBO cost vs. real cost, 26 cost, definition, 26 cost-estimating algorithm accuracy, object statistics, 27 DML or DDL statements, 25 execution plan cost, definition, 25 optimal, 26 suboptimal,

3 Index optimization process (see Optimization process, CBO) RBO, 25 Cursor cache, 41, 42 child, 42 parent, 42 D Database administrators (DBAs), 7 Data Definition Language (DDL) statements, 25 Data densification avoiding, analytics, description, 469 textbook solution, 470 Data dictionary views description, 437 inefficiencies with complex views, Data flow operators, 155 Data manipulation language (DML), 9 Data-type conversions coding problem, 432 implicit, DBAs. See Database administrators (DBAs) DBMS_STATS.COPY_TABLE_STATS advantages, 547 BUSINESS_DATE, 553 HIGH_VALUE and LOW_VALUE, 553 partition statistics, 547 SQL statements, 553 STATEMENT_PART, 550, 552 TRANSACTION_DATE, 552 DBMS_STATS.SEED_COL_USAGE, DBMS_XPLAN formatting options BASIC +ALLSTATS, DBMS_XPLAN packages, 128 DDL. See Data Definition Language (DDL) statements Degree of parallelism (DOP) auto DOP, 29 ideal DOP, 31 Denormalization bitmap join indexes, manual aggregation and join tables, 419 materialized views, 419 SQL performance tuning, 403 Disk-based sorts manually increasing size, memory, 448 memory allocation, 448 sort run, 446 three-pass sort, 447 two-pass sort, DML. See Data manipulation language (DML) DOP. See Degree of parallelism (DOP) Duplicate sorting, E EBR. See Edition-based redefinition (EBR) Edition-based redefinition (EBR), 481 Enterprise Manager (EM), 75 Equality vs. inequality predicates inappropriate use, inequality operator, MOSTLY_BORING, 429 NULL use, Errors, hints CHANGE_DUPKEY_ERROR_INDEX, 483 EBR, 481 IGNORE_ROW_ON_DUPKEY_INDEX, 483 integrity constraint, 483 ORA error, 483 rows and columns, 482 Exadata, 403 Execution plans adaptive plans, CBO calculation, 167 column projection, 142 controlling parallel execution, , 153 creating tables and loopback database link, 129 data flow operators, 155 DBMS_XPLAN.DISPLAY, 129 DBMS_XPLAN formatting options, DBMS_XPLAN functions, 174 DDL statements, 149 default display, 127 displaying plans AWR, 37, cursor, 42 DBMS_XPLAN.DISPLAY_CURSOR, 41 in cursor cache, 37, 41 pstart and pstop columns, 42 SH example schema and cursor cache, 42 distribution mechanisms, FORCE PARALLEL QUERY, global hints, 127 granules, hinting data dictionary views, multiple DFO trees, NO_MERGE hint, 168, notes, 148 operations coroutines, concept, 44 costs, 46 INLIST ITERATOR and PARTITION RANGE operators, 46 interactions, 44 operation 0\: SELECT STATEMENT, 44 operation 1\: SORT AGGREGATE, 45 operation 2\: TABLE ACCESS FULL, 45 operation 3\: HASH JOIN,

4 index Execution plans (cont.) operations 4 and 5\: TABLE FULL SCANs, 45 parent-child relationships, 44 optimizer hints, 127 ORCL, 129 outline data, PARALLEL and PARALLEL_INDEX, 166 parallel query server sets and DFO trees, peeked binds, 139, 141 predicate information, query blocks and object alias, 129, , , 168 remote SQL, 143 result cache information, 147 running EXPLAIN PLAN, 129 SEL$F1D6E378, 168 SQL Language Reference manual, 168 statement queuing and DOP downgrade, 167 table queues and DFO ordering, transformation, 171 EXPLAIN PLAN. See also Execution plans access predicate, 40 EMP and DEPT tables, 37 execution plans, 37 filter predicate, 40 misleading, 40 operation table, 39 F Final state optimization access method hash joins, nested loops, 301 IN list iteration execution plan, no iteration, 302 execution plan, with iteration, 303 join method inferior execution plan, 299 non-intuitive, join order inappropriate, 297 simple, Full table scan (FTS) bytes, 176 cardinality, 176 cost, 176 G Globally partitioned index, 413 Global statistics, Oracle STATEMENT_PART, TRANSACTION_DATE, 556 TSTATS.ADJUST_COLUMN_STATS_V2, 555 H Hash joins, 267, 269 Hints data and database, 477 DML error logging, 478 documented versus undocumented CARDINALITY hint, 479 EXPAND_GSET_TO_UNION, 479 GATHER_PLAN_STATISTICS, 479 SQL, 479 EBR, 481 errors, MODEL clause, optimizer hints (see Optimizer hints) Oracle SQL, 477 production-hinting (see Production-hinting) PUSH_SUBQ story, 478 runtime engine hints, I Ideal degree of parallelism (ideal DOP), 31 Ideal DOP. See Ideal degree of parallelism (ideal DOP) Index compression, 422 Index-organized tables (IOTs), 411 Index range and index full scans dimension table to avoid global index, 452 index to avoid sort, 451 local index to sort data, failure, 452 Index statistics bitmap index, 191 cost table access factors influencing, strong clustered index, 188 weak clustered index, 188 function-based index TIMESTAMP WITH TIME ZONE, 190 Universal Coordinated Time (UTC), 191 index operations, 187 nested loop access via multi-column index, 190 parameters, IN list iteration, Interested transaction list (ITL), 414 IOTs. See Index-organized tables (IOTs) ITL. See Interested transaction list (ITL) J, K, L Join orders hash join full outer, 277 hash join right outer, 277 with hash join input swapping, without hash join input swapping,

5 Index Join predicate pushdown (JPPD) transformation, 519 Joins anti-joins (see Anti-joins) cartesian joins, 272 description, 261, 293 hash, join orders (see Join orders) merge joins, nested loops (see Nested loops) parallel joins (see Parallel joins) semi-joins (see Semi-joins) SQL analytic function, 23 ANSI, 16, 21 Cartesian join, 21 CBO, 16 data densification, 24 four table inner join, 17 full outer join, 22 input swapping, 19 outer joins and ANSI join syntax, proprietary syntax, 20 right outer join syntax, 21 row source, 19 sales query, 23 table join, 16 traditional syntax, 16 JPPD. See Join predicate pushdown (JPPD) transformation M Manual Segment Space Management (MSSM), 412 Memory limit sorts, 445 Merge joins, MODEL clause and Excel, comparison, CURRENT_VALUE (CV), 125 DIMENSION BY clause, 125 execution plan, MEASURES clause, 125 MEDIAN, PARTITION BY clause, 125 RULES clause, 125 spreadsheet concepts, 122 N Nested loops left lateral joins, traditional, , 266 Non-sorting aggregate functions index range and index full scans (see Index range and index full scans) ROW_NUMBER, sorting rows with FIRST_VALUE aggregate function, sort with FIRST function, 450 Non-sorting aggregate functions (NSAFs) hash aggregation, 106 in analytics, 110 SORT GROUP BY, 107 NSAFs. See Non-sorting aggregate functions (NSAFs) O Object statistics CBO data dictionary information, 227 information, sources, 225 initialization parameters, system statistics, 226 column. See Column statistics creation exporting and importing, 177, gathering, indexes and tables, 181 setting, 181 transferring, 180 examining data dictionary, export table, 183 index (see Index statistics) locking, 220 pending, , 225 purpose (see Full table scan (FTS)) restoring, statistics and partitions and subpartition-level statistics, 207 execution plans, gathering, partitioned tables, gathering statistics, 211, global statistics, 210 NUM_DISTINCT calculations, 209 partition-level statistics, CBO, partition size, 215 synopses, 211 table (see Table statistics) Object statistics and deployment CBO Connor McDonald s view, Dave Ensor paradox, 82 strategic features, 81 concurrent execution plans multiple execution plans, 89 multiple SQL_IDs, creation, 90 skewed data and histograms, SQL statement, 91 workload variations,

6 index Object statistics and deployment (cont.) extended statistics, 96 gathering statistics, execution plans, 82 87, 94 generating false object statistics, 97 hand-crafted histograms, 97 multiple SQL statement altering statistics, 96 physical database changes, 96 transforming SQL code and adding hints, 96 Oracle s plan stability features SQL plan baselines, SQL profiles, 91 stored outlines, 91 performance management, principle airport example, 80 non-database deployment strategies, 80 Royal Mail example, 79 SLAs, 80 PL/SQL code, 97 single SQL statement adding hints to SQL code, 95 physical database changes, 95 transforming SQL code, 95 TCF, TSTATS column statistics, description, 92 Real World Performance team, 94 time-sensitive data, removal, unchanged execution plans, 87 One-pass sort, 447 Optimization process parallelism ALTER SESSION statement, 29, 31 auto DOP, 29, 31 final state query optimization, 34 ideal DOP, 31 PARALLEL optimizer, 29, 31 parallel query operations, query transformation cost-based transformation, 32 heuristic transformation, simple view merging, Optimizer hints CARDINALITY and OPT_ESTIMATE hints, , CBO, 486 FIRST_ROWS and ALL_ROWS, object statistic hints, OPT_PARAM, 486, 488 PARALLEL (T), 486 Oracle column statistics (see Column statistics) DBMS_STATS, 525 DBMS_STATS.COPY_TABLE_STATS (see DBMS_STATS.COPY_TABLE_STATS) global statistics, management and commitment, 526 re-gathering statistics, 526 table partitions, 556 Outline data comments, 139 execution plan, 136 identification, INSERT, 136 interpretation hints, 137 OUTLINE_LEAF and OUTLINE, 139 query blocks, 136 query transformation hints, 139 SQL statements, 139 types of hints, 137 P Parallel DDL, Parallel DML, Parallel joins adaptive, bloom filtering, broadcast distribution, data buffering, full partition-wise joins, hash distribution, partial partition-wise joins, PQ_DISTRIBUTE, 282 row source replication, Parallel query, Parallel query server set (PQSS) by running DFO Q1, 00 and PQSS2 starts, 158 DFO tree, 157, 160 hash distribution, 289 hash join, 285 join predicate, 284 partition granules, 284 PQ_FILTER hint parameter, 165 TQ10001, TQ10002 and TQ10003, 160 Parallel sorting, Partition granules, 154 Physical database design adding indexes, 403 compression index, 422 LOB, 422 table, 423 contention, management hot block problem, 412 sequence contention, 412 denormalization, LOBs,

7 Index partitioning advantages, 415 full table scans, 415 parallelization, 418 partition-wise joins, removing indexes DML, 404 foreign key constraints, 405 V$OBJECT_USAGE, 404 required indexes identification bitmap indexes, data, global partitioned indexes, 413 INDEX FULL SCAN, 411 IOTs, 411 multi-column non-unique indexes, correct use, 407, 409 order of columns, multi-column index, 409 Performance Tuning Guide, 405 reverse key indexes, 412 single-column non-unique B-tree indexes, misuse, Plan evolvement, 92 PL/SQL, 125 PQSS. See Parallel query server set (PQSS) Predicates equality vs. inequality, join when function applied to column, 427 partition elimination and expressions, 426 Prefix table, 422 Production-hinting bushy join, 496, COUNTRY_SALES_TOTAL, database_block_corruption, 506 data piecemeal, 503 execution plans, 504 materialization, NO_ELIMINATE_OBY, 505 NO_QUERY_TRANSFORMATION, 505 SH.CUSTOMERS, 502 tablespace consumption, 505 Q Query blocks and object alias CBO, 130 merging, 131 multiple types, multi-table insert, 133 simple query, 130 single-table INSERT statement, 135 tables T1 and T2, 130 the ALIAS section, 135 the QB_NAME hint, 132 Query blocks and subqueries definitions, 101 logical order, 102 ORDER BY clause, 102 set query block, 102 R RBO. See Rule-based optimizer (RBO) Readability, SQL DML statements, 10 inline views, 10 JID, 12 Oracle database, 13 tables/data dictionary, 11 Relative data block address (RDBA), 231 Remote SQL, 143 Rewriting, SQL statement bind variables, 432 data dictionary views, data-type conversions, expressions, predicates (see Predicates) multiple similar subqueries, temporary tables (see Temporary tables) UNION, UNION ALL and OR, , Root cause analysis (RCA), 65 ROWID pseudocolumn, 507 ROWIDs BATCHED ROW ACCESS, 233 bigfile tablespaces, 232 extended, 232 formats, 231 function with LAST function, optimistic locking, 235 Oracle database, 455 range of rows, table, 236 restricted ROWID for smallfile tablespaces, parts, 231 single, table access, 234 sorting fewer columns, sorting, un-indexed column, 455 table access, methods, 233 universal, 232 Rule-based optimizer (RBO), 25, 81 Runtime engine operational level data, display ALL executions of a statement vs. operation, 51 DBMS_XPLAN.DISPLAY_CURSOR, 50 V$SQL_PLAN_STATISTICS_ALL, operation level data, collection GATHER_PLAN_STATISTICS, SQL statement, 47 SQL tracing, 47, 49 STATISTICS_LEVEL to ALL,

8 index Runtime engine (cont.) optimal, one-pass, and multipass operations, 57 shortcuts function result cache, 61 join shortcuts, 59 OCI cache, 61 result cache, scalar subquery caching, 58 Snapper, session level statistics, SQL performance monitor DBMS_SQLTUNE.REPORT_SQL_ MONITOR, report, 55 V$SQL_PLAN_STATISICS_ALL, drawbacks, 53 transaction consistency and function calls, workareas memory allocation, 56 operations, 55 WORKAREA_SIZE_POLICY, AUTO, 56 WORKAREA_SIZE_POLICY, MANUAL, 57 Runtime engine hints APPEND_VALUES hint, 484 CBO, 483 DBMS_XPLAN.DISPLAY_CURSOR, 485 DML statements, 484 DRIVING_SITE, 483 EBR, 486 GATHER_OPTIMIZER_STATISTICS hint, 486 GATHER_PLAN_STATISTICS, 483 MONITOR hint, 483 NO_SET_TO_JOIN, 486 OPTIMIZER STATISTICS GATHERING, 483 ORA-12838, 486 S SALES_ANALYTICS, 464 SecureFiles and Large Objects Developer s Guide, 424 Semi-joins null-accepting, 279 standard, Service Level Agreements (SLAs), 65, 80 SLAs. See Service Level Agreements (SLAs) Sort optimization. See also Data densification adding additional predicates, optimize analytics, 463 description, 445 disk-based sorts, duplicate sorting, first attempt at moving average, 462 inefficient implementation, SALES_ANALYTICS, 464 lateral joins, data dictionary types, lateral joins with one dimension table, lateral joins with two dimension tables, memory limits, 445 non-sorting aggregate functions (see Non-sorting aggregate functions) optimal, 445 ORDER BY clause, 445 pagination problem, parallel sorting, ROWIDs (see ROWIDs) SQL features array interface, 3, 7 9 AWR, 6 bind variable, 5 CBO, 3 computation, 3 DBA_HIST_SQLTEXT, 6 DBMS_SQLTUNE_UTIL0, 5 EMPLOYEE_ID, 4 HR.EMPLOYEES, 4 joins (see Joins, SQL) literals, 4 NUL character, 6 Oracle Database, 4 SELECT statement, 5 SQL_ID, 4 subquery factoring (see Subquery factoring, SQL) tuning process, 3 V$SQL, 6 VARCHAR2 string, 5 SQL functions aggregate functions and analytics, combination, GROUP BY and analytic functions, multiple sorts, comparison, 111 non-sorting (see Non-sorting aggregate functions (NSAFs)) PARTITION BY, 110 queries, 104 sorting, analytic functions and aggregation, separating with subqueries, 120 COUNT function, 110 execution plans, order by sub-clause, query partition sub-clause, ROWNUM and subqueries, 109 ROW_NUMBER and RANK, 111 subqueries, use, 108 windowing sub-clause, categories, 103 single-row functions, 121 SQL performance monitor DBMS_SQLTUNE.REPORT_SQL_MONITOR, report, 55 V$SQL_PLAN_STATISICS_ALL, drawbacks,

9 Index Subquery factoring, SQL CBO, 15 data dictionary, 9 MGR_COUNTS, 14 multiple times, 13 MYPROFITS, 10 PEERS, 14 readability, 10 11, 13 recursion, SUBORDINATES, 14 UNIT_COST, 9 T Table compression basic, 423 hybrid columnar compression, 423 OLTP, 423 overriding PCTFREE, Table statistics information, sources (CBO), parameters, 184 restoring statistics, TCF. See Tuning by Cardinality Feedback (TCF) Temporary tables description, 438 effort duplication, repeated construct, multiple SQL statements, Three-pass sort, 447 Transitive closure, TSTATS column statistics, 92 93, 573, 575 description, 92 execution plans, 525 ORACLE (see ORACLE) partition-elimination anomalies cardinality estimation, 567 CBO, 557 columns and indexes, 565 DBMS_STATS.EXPORT_TABLE_STATS, 561 dynamic sampling, 565 ETL processes, 564 hash join, 570 maintenance operations, 557 MERGE statements, 567 NUM_BLOCKS, 562 NUM_DISTINCT, 569 NUM_PARTITIONS, 557 permanent table, 565 PMOP, 561 statistics-gathering process, 561 TSTATS.ADJUST_TABLE_STATS, 561 production systems, 525 Real World Performance team, 94 time-sensitive data, removal, TSTATS deployment approach, 178 Tuning by Cardinality Feedback (TCF), 87 Tuning, SQL statement analysis elapsed time, performance analysis, runtime statistics, 71 statement completion, business problem, changing code adding hints, 73 adding information, 73 changes to environment, 75 physical changes to database, 74 SQL Tuning Advisor, data, 67 gathering statistics, SQL statement, 66 technical problem, 66 Two-pass sort, 447 U, V, W, X, Y, Z UNION, UNION ALL and OR avoiding dynamic SQL with, different results, equivalent statements with different plans, Universal Coordinated Time (UTC), 191 Unsupported transformations,