Oracle 12.2 My Favorite Top Five New or Improved Features. Janis Griffin Senior DBA / Performance Evangelist

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1 Oracle 12.2 My Favorite Top Five New or Improved Features Janis Griffin Senior DBA / Performance Evangelist

2 Who Am I Senior DBA / Performance Evangelist for SolarWinds Janis.Griffin@solarwindscom Twitter Current 25+ Years in Oracle, SQL Server, ASE, MySQL DBA and Developer Specialize in Performance Tuning Review Database Performance for Customers and Prospects Common Question How do I tune it?

3 Agenda In-Memory Option How it works Virtual Columns, join groups SQL, Dictionary, and Optimizer Enhancements New Functions and Syntax Approximate and First n Rows SQLPlus Improvements PDB Improvements Hot Clone Memory Management New Partitioning Features Sharding Capabilities The Horizontal Database

4 Memory In The Beginning 9i - SGA_MAX_SIZE Memory could grow/shrink DB_CACHE_SIZE No more DB_BLOCK_BUFFERS 10g - Automatic Shared Memory Management (ASMM) SGA_TARGET Set minimum values for Data Cache, Large Pool Shared Pool, Java Pool 11g - MEMORY_TARGET (AMM) Sets SGA + PGA size together Can still control minimum sizes - e.g., PGA_AGGREGATE_LIMIT (new in 12c) 12c - INMEMORY_SIZE Set the size of IN-MEMORY Column Store

5 12c In-Memory Option Designed for mixed workloads Can combine OLAP with OLTP queries No more Data Warehouse (maybe) Dual-format architecture doesn t double memory requirements Approximately less than a 20% additional memory overhead No additional storage costs or synchronization issues No changes to application code Optimizer is fully aware of the column format Routes analytic queries to the column format OLTP operations to the row format Only objects with the INMEMORY attribute Can be in the IN-Memory Column Store (IM) Works on tablespaces, tables, partitions, sub-partitions or materialized views

6 12c In-Memory Option Transactions in Buffer Cache Analytics in In-Memory Column Store

7 IM Why Use it? Access only the column data needed Can prioritize when IM is populated Partially load some columns at startup Load other columns when accessed ALTER TABLE customers INMEMORY PRIORITY CRITICAL; In compressed format Saves space Can scan or filter compressed data Only decompressed when used in the result set CREATE TABLE test (c1 NUMBER, c2 NUMBER, c3 CLOB) INMEMORY MEMCOMPRESS FOR QUERY NO INMEMORY(c3), INMEMORY MEMCOMPRESS FOR CAPACITY HIGH (c2); DBMS_COMPRESSION (advisor) Now supports IM compression

8 IM Why So Fast IM is made up of multiple In-Memory Compression Units (IMCUs) Background worker processes allocate their own IMCUs Then populates their subset of database blocks Works with the IMCO (In-Memory Coordinator) background process Uses SIMD Vector processing Definition: Single Instruction processing Multiple Data values Allows a set of column values to be evaluated simultaneously in one CPU instruction Look at V$STATNAME IM scan CUs columns accessed, New in 12.2 IM FastStart Allows for checkpoint of IMCUs to FastStart area on disk Takes up storage space but less CPU intensive on startup BEGIN dbms_inmemory_admin.faststart_enable('fs_tbs'); END; 'IM scan segments minmax eligible', 'IM scan CUs pruned'); Best for queries that scan large amounts of data or compute values on the fly

9 IM Why So Fast IM Storage Indexes Automatically created and maintained on each column in the column store Allow pruning to occur based on filter predicates in the query Keeps track of min/max values for each column in an IMCU Helps to avoid scans of IM column store New in In-Memory Expressions Materialize commonly used expressions Prevents re-computation for every row Are derived values that take advantage of IM Can be done in one of 2 ways Expression Statistics Store(ESS) automatically stores top 20 popular expressions Manage with DBMS_INMEMORY_ADMIN package Set with INMEMORY_EXPRESSIONS_USAGE parameter In-Memory Virtual Columns Needs INMEMORY_VIRTUAL_COLUMNS parameter set to ENABLED or MANUAL

10 IM - How To Use It IM column store is disabled by default (requires re-start) Set INMEMORY_SIZE parameter to enable Needs to be set to 100mb or higher New in Can increase on the fly at 128mb or higher Part of SGA May need to increase SGA_TARGET / MEMORY_TARGET

11 IM - Enable It

12 IM How To Use It Objects must have the INMEMORY attribute to use the IM column store Can be tablespace, table, (sub)partition or materialized view To view objects in column store see V$IM_SEGMENTS, V$IM_COLUMN_LEVEL, any V$IM% views

13 IM Performance No IM IM

14 IM Virtual Columns Example New 12.2 Feature alter system set inmemory_virtual_columns = ENABLE;

15 IM Joins In-Memory Joins Bloom Filters (10g) Transforms join into a filter if there are filtering predicates Can be used in column format via SIMD vector processing New in 12.2 Join Groups Can be used when there are no filtering predicates Allow join columns from multiple tables to share a single compression dictionary Hash joins don t have to decompress the data first View join groups in USER_JOINGROUPS View shared dictionary in v$im_segdict CREATE INMEMORY JOIN GROUP jgroup_name(order_item(ol_i_id),item(i_id));

16 IM Join Group Example Cont. SELECT ol_o_id,ol_number, ol_delivery_d, i_name, i_price FROM order_item, item WHERE ol_i_id = i_id and i_price < 2.00; Join Groups share the same compression dictionary This allows for joins to occur on compressed values Doesn t need to decompress and hash the data Join columns above are order_item.ol_i_id and item.i_id Tables need to be reloaded after the Join Group creation To create the common compression dictionary, called Global Dictionary Ensure the Global Dictionary exists by checking V$IM_SEGDICT_GD SELECT o.object_name table_name, c.column_name column_name, gd.head_address "GD Address" FROM user_objects o, user_tab_columns c, v$im_segdict gd WHERE gd.objn = o.object_id AND o.object_name = c.table_name AND gd.column_number = c.column_id;

17 IM Join Group Example New 12.2 Feature Using Bloom Filter / Join Group? No IM

18 IM Join Group Example Finding join group usage Need to use SQL_MONITOR - dbms_sqltune.report_sql_monitor_xml or OEM Query needs SELECT /*+ MONITOR */ hint Columnar encodings leveraged = 1 Columnar Encodings Leveraged

19 New SQL 12.1 FETCH FIRST n ROWS ONLY Retrieves first rows without scanning everything Faster OFFSET n ROWS FETCH FIRST n ROWS ONLY Skip some number of rows

20 New SQL 12.2 Approximate Query Processing Used for approximate count distinct values and adds percentile aggregation Allows for faster processing of large data sets Not exact but usually within 95%+ range Three new parameters alter system/session approx_for_aggregation Default=FALSE Can be overridden by the next 2 parameters If true, sets approx_for_percentile=all approx_for_count_distinct Default=FALSE Overrides exact COUNT DISTINCT clause approx_for_percentile Default=NONE Overrides MEDIAN clause (PERCENTILE_CONT) Values can be PERCENTILE_CONT, PERCENTILE_DISC, and ALL Can be used without any changes to existing code Replaces exact functions with SQL functions (next page) that return approximate results

21 New SQL functions in 12.2 Approximate query functions APPROX_COUNT_DISTINCT (Introduced in 12.1) APPROX_COUNT_DISTINCT_DETAIL APPROX_COUNT_DISTINCT_AGG TO_APPROX_COUNT_DISTINCT APPROX_MEDIAN APPROX_PERCENTILE APPROX_PERCENTILE_DETAIL APPROX_PERCENTILE_AGG TO_APPROX_PERCENTILE Also in 12.2, support for Materialized Views and Query Rewrite VALIDATE_CONVERSION Determines if a given input value can be converted to a requested data type Simplifies coding

22 Approximate SQL Example 95% accurate

23 Approximate SQL Example With Changing Code Why is it exact? Need to set both

24 Approximate Percentile Example With Changing Code 99.68% accurate

25 12.2 Dictionary Improvements and Other New Stuff Object identifiers have increased from 30 bytes to 128 bytes Such as users, roles, tables, columns, indexes, constraints, etc Changed in dictionary views - instead of VARCHAR2(30), now VARCHAR2(128) May affect your reporting Exceptions: Disk groups, pluggable databases (PDBs), rollback segments, and tablespaces still 30 bytes Names of databases are still limited to 8 bytes SQLPlus Improvements HISTORY SET HIST[ORY] {ON OFF n} SHOW HISTORY RUN n SET ROWPREFETCH {1 n} / SET LOBPREFETCH {0 n} SET STATEMENTC[ACHE] {0 n}

26 12.2 Optimizer Changes New init.ora parameters OPTIMIZER_ADAPTIVE_PLANS (Default = TRUE) Adaptive joins Bitmap pruning Parallel distribution method OPTIMIZER_ADAPTIVE_STATISTICS (Default = False) SQL Plan Directives (SPDs) for query optimization Statistics feedback (for joins only) Adaptive dynamic sampling for parallel queries Performance feedback Obsolete OPTIMIZER_ADAPTIVE_FEATURES

27 12.2 Optimizer Changes SQL Plan Directives Control of Auto Creation of Column Group Statistics New DBMS_STATS preference AUTO_STAT_EXTENSIONS (DEFAULT=OFF) EXEC DBMS_STATS.SET_GLOBAL_PREFS('AUTO_STAT_EXTENSIONS','ON') Can view in DBA_STAT_EXTENSIONS select owner, table_name, extension, extension_name from dba_stat_extensions where creator = 'SYSTEM' order by owner,table_name,extension_name;

28 Multitenant Changes in 12.2 Can create a hot clone of PDB No downtime for PDB being cloned Uses redo then undo for all committed / uncommitted transactions Local undo required Undo can now exist in PDB Archive logging must be enabled Can create a refreshable PDB (for VLDBs) Built on top of hot clone Golden master for snapshot clones Automatically or manually refreshed from redo Opened in read-only mode Can relocate PDBs to different CDBs online Built on top of Refreshable PDB Great way to load-balance Can help maintain SLAs for performance and availability

29 Multitenant Changes in 12.2 Can have 4096 PDBs per CDB Instead of original 252 Can flashback a single PDB Doesn t have to use local undo but easier than shared undo Can use SCN, restore point, clean restore point or guarantee restore point View SCNs in V$FLASHBACK_DATABASE_LOG FLASHBACK PLUGGABLE DATABASE pdb1 TO TIMESTAMP some_date; Data Guard now supports individual PDB-level failover Used to be all PDBs or none Now can set parameter ENABLED_PDBS_ON_STANDBY on standby database Examples *, PDB?, PDB*, -PDB1

30 New Memory Settings At PDB Level If using Database Smart Flash Cache Can set CDB resource plan to allocate memory between PDBs MEMORY_LIMIT percentage that limits PDB memory usage MEMORY_MIN percentage guaranteed for PDB memory usage Can set INMEMORY_SIZE at PDB Can be over-subscribed

31 12.2 Partitioning Features Read-only partitions Useful for old partitions Use READ ONLY READ WRITE (default) Can use CTAS or ALTER

32 12.2 Partitioning Features Convert Non-partitioned table To a partitioned table ONLINE UPDATE INDEXES clause is optional. Indexes with SYS names will be generated if not used

33 12.2 Partitioning Features Automatic List Partitions Requires creation of first partition No default partitions Multi-column List Partitions Can only have one default partition

34 12.2 Partitioning Features Filtered Partitions for Maintenance Operations Helps with partition pruning and data cleanup MOVE PARTITION MERGE PARTITION SPLIT PARTITION Can do ONLINE Other New Features For exchange with clause Partitioned external tables 12.2-partition-create-tables

35 12.2 Sharding Feature Sharding horizontally partitions data across independent databases A share nothing architecture CPU, memory, disk Each database is known as a shard All shards together make up a logical database Called sharded database (SDB) Intended for custom OLTP applications that: Have a well-defined data model Have a data distribution strategy (consistent hash, range, list, or composite) Primarily access data using a sharding key e.g., customer_id, account_no, or country_id

36 12.2 Sharding Feature Benefits of Sharding Linear scalability for performance and capacity Eliminates single points of failure Nothing is shared Geographical distribution of data Data is closer to consumers (e.g. Facebook) Satisfies regulatory requirements Simplifies Cloud Deployment Easy to do rolling upgrades Examples of Companies Online payment systems Regulatory requirements Airline ticketing systems Social media companies

37 Other SDB Components Shard Catalog An Oracle database that centralizes management of a SDB Supports automated shard deployment Handles multi-shard queries Holds master copy of duplicated table Shard Directors Network listeners which route connections based on a sharding key Connection pools can act as shard directors for pooled connections Global service An extension of database services for the SDB Management Interfaces GDSCTL (command-line utility) and OEM

38 SDB Architecture To install, download Oracle Database 12c Release 2 : linuxx64_12201_database.zip Oracle Database 12c Release 2 Global Service Manager : linuxx64_12201_gsm.zip

39 Summary Oracle 12.2 provides a lot of new features and enhancements This presentation only touches on a few In-Memory virtual columns Helps speed up analytical queries New approximate functions Great if you don t need exact answers PDB hot cloning Online partitioning Sharded database (SDB) or the Horizontal database Good news it s been around in the Cloud for quite sometime Became available for on-premise in March 2017 Hopefully many of the bugs have been worked out Try it out and tell me which new feature you like best me at janis.griffin@solarwinds.com

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