Extreme Data Warehouse Performance with Oracle Exadata

Transcription

1 Managed Services Cloud Services Consul3ng Services Licensing Extreme Data Warehouse Performance with Oracle Exadata Kasey Parker Enterprise Architect

2 Who is Centroid? QUICK FACTS Centroid is a leading provider of Oracle Technology, Applica8ons and Infrastructure/Hos8ng solu8ons Established in 1997 Office loca8ons: Troy, MI (HQ); San Francisco, CA; Los Angeles, CA; Dallas, TX 200+ Consultants Oracle Pla8num Partner Selected to Oracle s Top 25 Strategic Partner Program Top 5 Oracle Partner for Hardware/Storage 100% Oracle Red Stack Focused Clients for life approach to customer rela8onships Oracle Exadata Center of Excellence established in 2011 Centroid Authored - Oracle Exadata Recipes (Published Feb- 2013)

3 Agenda Exadata Overview Why Exadata? Exadata s Secret Sauce GeAng the Most out of Exadata DW Avoiding the 3X Club Other Data Warehouse Best Prac3ces

4 EXADATA OVERVIEW

5 Exadata Architecture Database hardware and soiware plakorm in a box Scale- Out Database Servers 8x 2- socket, or 2x 8- socket Xeon database servers Oracle Database, ASM, RAC; Linux or Solaris Standard Ethernet to data center Scale- Out Intelligent Storage Servers 2- socket storage servers, Exadata Storage SoIware Up to 672 terabytes disk per rack 56 PCI Flash memory cards per rack InfiniBand Network Unified internal connec3vity ( 40 Gb/sec )

6 Exadata Configura3on Op3ons Start small and grow as needed upgraded onsite Eighth Rack Quarter Rack Managed Services Cloud Services Consul3ng Services Licensing Half Rack Full Rack

7 Exadata Hardware Summary X4-2 Full X4-2 Half X4-2 Quarter X4-2 Eighth Database Servers Database Grid Cores Database Grid Memory (GB) 2048 (max 4096) 1024 (max 2048) 512 (max 1024) 512 (max 1024) InfiniBand switches Ethernet switch Exadata Storage Servers Storage Grid CPU Cores Raw Flash Capacity 44.8 TB 22.4 TB 9.6 TB 4.8 TB Raw Storage Capacity Usable mirrored capacity Usable Triple mirrored capacity High Perf 200 TB 100 TB 43.2 TB 21.6 TB High Cap 672 TB 336 TB 144 TB 72 TB High Perf 90 TB 45 TB 19 TB 9 TB High Cap 300 TB 150 TB 63 TB 30 TB High Perf 60 TB 30 TB 13 TB 6.3 TB High Cap 200 TB 100 TB 43 TB 21.5 TB

8 Exadata Hardware Exadata X4-2 SQL IO Performance Flash Cache SQL Bandwidth 1,3 Flash SQL IOPS 2,3 Disk SQL Bandwidth 1,3 Disk SQL IOPS X4-2 Full Rack X4-2 Half Rack X4-2 Quarter X4-2 Eighth High Cap Disk 100 GB/s 50 GB/s 21.5 GB/s 10.7 GB/s High Perf Disk 100 GB/s 50 GB/s 21.5 GB/s 10.7 GB/s 8K Reads 2,660,000 1,330, , ,000 8K Writes 1,960, , , ,000 High Cap Disk 20 GB/s 10 GB/s 4.5 G/s 2.25 GB/s High Perf Disk 24 GB/s 12 GB/s 5.2 GB/s 2.6 GB/s High Cap Disk 32,000 16,000 7,000 3,500 High Perf Disk 50,000 25,000 10,800 5,400 Data Load Rate 4 20 TB/hr 10 TB/hr 5 TB/hr 2.5 TB/hr 1 - Bandwidth is peak physical scan bandwidth achieved running SQL, assuming no compression. Effec3ve data bandwidth will be much higher when compression is factored in. 2 - IOPS Based on read IO requests of size 8K running SQL, typically with sub- millisecond latencies. Note that the IO size greatly effects flash IOPS. Others quote IOPS based on 2K, 4K or smaller IOs that are not relevant for databases and measure IOs using low level tools instead of SQL. 3- Actual Performance varies by applica3on. 4 Load rates are typically limited by database server CPU, not IO. Rates vary based on load method, indexes, data types, compression, and par33oning

9 WHY EXADATA?

10 Why Exadata? Exadata is designed to eliminate the most common bomleneck for large databases Timely transfer of large data sets from storage subsystem to database server

11 Why Exadata? Solving the IO BoTleneck Solu3on 1: Enlarge the pipe Physical disks, on all cells, work in parallel to serve IO requests Large Infiniband pipe (40GB/Sec)

12 Why Exadata? Can t we do that with other high performance storage soluvons? YES There is nothing Magical about Exadata hardware, and it s s3ll the same Oracle Database

13 Why Exadata? Solving the IO BoTleneck Solu3on 2: Reduce the IO opera3ons Done using Exadata s Secret Sauce: Smart Storage, Smart Flash Cache and Hybrid Columnar Compression 10X reduc3on in data sent to database servers is common

14 Exadata Innova3ons Some are automa3c, with limited configura3on ability Storage Indexes Smart Flash Cache Some may require some effort Smart Scans Hybrid Columnar Compression (HCC) IORM (Resource Manager)

15 Storage Indexes Transparent I/O Elimination with No Overhead Table A B C D Index Min B = 1 Max B =5 Min B = 3 Max B =8 Exadata Storage Indexes maintain summary information about table data in memory Store MIN and MAX values of columns Typically one index entry for every MB of disk Eliminates disk I/Os if MIN and MAX can never match where clause of a query Completely automatic and transparent Select * from Table where B<2 - Only first set of rows can match

16 Smart Flash Cache I/Os 2.66 Million 8K Read 1.96 Million 8K Write IOPS from SQL Caches Read and Write I/Os in PCI flash Transparently accelerates read and write intensive workloads Up to 2.66 million 8K read IOPS from SQL Up to 1.96 million 8K write IOPS from SQL Persistent write cache speeds database recovery Exadata Flash Cache is much more effec3ve than flash 3ering architectures used by others Caches current hot data, not yesterday s Caches data in granules 8x to 16x smaller than 3ering Greatly improves the effec3veness of flash Other Flash Features can be configured if needed E.g. Cache compression, Cache pinning, Flash Disks (for Temp)

17 Avoid the 3X Club Some Exadata op3miza3ons may require a limle effort but they re worth it. Data Warehouse workloads should improve >7X on Exadata

18 Avoid the 3X Club Tune for Smart Scans Wisely use Parallelism Compress with HCC where appropriate Invoke Resource Management (IORM) S3ll follow Data Warehouse Best Prac3ces

19 Avoid the 3X Club an Example EDW for Large Organiza3on in Salt Lake valley Moved to Exadata beginning September 2012 Configured/Tuned Exadata op3miza3ons for October 2012 Average Response Time

20 Avoid the 3X Club Tune for Smart Scans Wisely use Parallelism Compress with HCC where appropriate Invoke Resource Management (IORM) S3ll follow Data Warehouse Best Prac3ces

21 Smart Scan Processing Who are my customers in Salt Lake City? Oracle DB Grid Select name, customer#... Where city= SALT LAKE CITY Exadata Storage Grid Smart Scan idenvfies rows / columns in the 1 TB tables that match the SQL (1000 rows) 1000 rows returned to client IO is executed and 20MB returned from storage to PGA

22 Smart Scan Comparison PGA SGA Rows and Columns Database Servers 8K Blocks Smart Scans Storage Servers Standard Operations 22

23 Smart Scan Requirements Full table scan or index fast full scan No IOTs, Clustered Tables or LOBs Direct path reads Direct path reads happen for Serial queries of large tables (11gR2) Func3on of Buffer Cache Size, threshold and object size» _small_table_threshold Parallel queries Queries when _serial_direct_read = TRUE!

24 Smart Scans How do you know? Execu3on Plan TABLE ACCESS STORAGE FULL Storage() predicate Only indicates Smart Scan is eligible to be performed; does not mean it is

25 Smart Scans How do you know? Sta3s3c views (V$MYSTAT, V$SESSTAT) cell physical IO bytes eligible for predicate offloading cell physical IO interconnect bytes cell physical IO interconnect bytes return by smart scan V$SQL views (IO_ columns) IO_CELL_OFFLOAD_RETURNED_BYTES IO_CELL_OFFLOAD_ELIGIBLE_BYTES Wait events cell smart table scan cell smart index scan

26 Smart Scans How do you know? A Easier Way SQL Monitor Accessed through DBMS_SQLTUNE or OEM

27 Smart Scans Why don t they happen? Index scan used instead Buffer cache too large Many table blocks in buffer cache Chained rows Tables with more than 255 columns Certain func3ons (see v$sqlfn_metadata) Table "too small (_small_table_threshold)! Read consistency Delayed block cleanout

28 Smart Scans How to get them? Accurate, Up- to- date Sta3s3cs Are ETL jobs gathering stats appropriately? Use auto sample size Exadata System stats This is how the op3mizer becomes Exadata aware exec dbms_stats.gather_system_stats('exadata');! Right Sized SGA Most Data warehouses shouldn t need more than 16GB Avoid row by row processing Appropriate use of Indexes Wise use of Parallelism

29 To Index or Not to Index So if Smart Scans are so great do we even need indexes anymore? YES!... You s3ll need indexes for queries with single/few out of many row reads Also keep many FK indexes especially if used for Star Transforma3ons

30 To Index or Not to Index Many indexes will be obsolete and should be removed to help drive smart scans Test by: Making indexes invisible and tes3ng queries Comparing ETL without indexes

31 Avoid the 3X Club Tune for Smart Scans Wisely use Parallelism Compress with HCC where appropriate Invoke Resource Management (IORM) S3ll follow Data Warehouse Best Prac3ces

32 Parallelism on Exadata Parallelism executes the same on or off Exadata PX works much bemer on Exadata and can be a big performance boost Pushes Direct Path Reads to enable smart scans Exadata architecture enables parallelism through storage cell CPUs and disks all working together Load split across DB and Cell CPUs Allows lower DOP on Exadata to achieve op3mal performance Easy to overwhelm a system with Parallelism But on Exadata, it can be controlled effec3vely

33 Parallelism Guidelines Control parallel load Parallel init parameters Parallel Statement Queuing DBRM resource plans Set parallel degree limits and max % targets Set parallel degree on large tables ALTER TABLE [TABLE NAME] PARALLEL 12; Use parallelism for direct path loads in ETL CTAS, IAS or Merge with Append Hint, Bulk Load API ALTER SESSION ENABLE PARALLEL DML;!

34 Key Parallel Init Parameters PARALLEL_MAX_SERVERS Max # of instance parallel workers Recommend leaving at default (CPU_COUNT * PARALLEL_THREADS_PER_CPU*10) PARALLEL_MIN_SERVERS See Oracle Support Note for Exadata best prac3ces Min # of instance parallel workers (default 0) Helps control overhead of crea3ng and destroying workers Recommend seang to high daily average of workers

35 Parallel Init Parameters AUTO DOP Enabled by parallel_degree_policy! Manual (Default), Limited, Auto Each statement automa3cally evaluated as a candidate for parallelism; whether or not statements contain parallel hints or objects have a DOP set Controlled by parallel_min_time_threshold 10 seconds by default Statements expected to run longer are candidates for automa3c paralleliza3on Use with Cau3on!

36 Parallel Statement Queuing Limits concurrent parallel processes un3l enough slaves are available Protects against overwhelming the server with parallel processes Delivers a more consistent performance profile Can be enabled without Auto DOP by seang _parallel_statement_queuing = TRUE! Control when queuing starts by using PARALLEL_SERVER_TARGET! Statements queued in FIFO method!

37 Parallel Statement Queuing

38 Parallel Statement Monitoring OEM / Grid Control! SQL Monitoring specifically GV$PX PROCESS One record per Parallel Worker GV$SQL_MONITOR Also shows queued parallel statements See Oracle Support Note for more monitoring queries

39 Avoid the 3X Club Tune for Smart Scans Wisely use Parallelism Compress with HCC where appropriate Invoke Resource Management (IORM) S3ll follow Data Warehouse Best Prac3ces

40 Hybrid Columnar Compression Data is organized and compressed by column in compression units (CU) Speed Optimized Query Compression for Data Warehousing 5X to 10X compression typical Runs faster because of Exadata offload! Space Optimized Archival Compression for infrequently accessed data 10X to 50X compression typical Query Benefits Mul3ply Faster and Simpler Backup, DR, Caching, Reorg, Clone

41 Hybrid Columnar Compression VENDOR_ID VEND_NAME STATE VNDR_RATING VENDOR_TYPE ========== =========== ===== =========== ========== 100 ACME ONE MI 100 DIRECT 101 ACME ONE CA 90 DIRECT 102 NORTON IA 95 INDIRECT 103 WINGDINGS MI 96 INDIRECT 104 WINGDINGS GA 96 INDIRECT Hybrid Columnar Compression Uncompressed Logical Compression Unit <- Header - > Free space 100ACME ONEMI100DIRECT 101ACME ONECA()DIRECT 102NORTONIA95INDIRECT 103WINGDINGSMS96INDIREC T 104WINGDINGSGA96INDIREC T CU Header- > VENDOR_ID VEND_NAME VNDR_RATING STATE VENDOR_ TYPE COL7 COL6 COL8 COL10 COL9

42 Hybrid Columnar Compression Performance Benefits If queries select a single or subset of columns, Oracle will only need to read from blocks on which the columns exist This is different than other types of compression and un- compressed tables Not only is space saved, but also IO Saving IO means bemer performance!

43 HCC Why Not? HCC requires direct path loads Conven3onal inserts use OLTP compression Deletes against HCC tables lock en3re CU When upda3ng HCC tables: The updated row is migrated (i.e., deleted + re- inserted into a new block, leaving a pointer behind) New row is OLTP- compressed Locks impact en3re CU, not just row! DML on HCC tables is very expensive!

44 HCC Use Cases Use OLTP compression for DW tables by default, and then use HCC compression when Data is direct path loaded (CTAS, Insert /*+ APPEND */) Data is not updated Or rarely updated and truncated and reloaded periodically Par33on tables with different compression ra3os Updated Data = OLTP compression Heavily Queried Data = Query / Archive Low compression Cold / Archive Data = Archive High compression Use compression advisor to preview compress ra3o DBMS_COMPRESSION.GET_COMPRESSION_RATIO

45 Avoid the 3X Club Tune for Smart Scans Wisely use Parallelism Compress with HCC where appropriate Invoke Resource Management (IORM) S3ll follow Data Warehouse Best Prac3ces

46 IORM IO Resource Management (IORM) governs and meters IO from different workloads in the Exadata Storage Servers A common challenge with shared storage infrastructure is that of compe3ng IO workloads Batch vs. OLTP Warehouse vs. OLTP Produc3on vs. Test and Development Compe3ng priori3es can be mi3gated by over- provisioning storage, but this becomes expensive Exadata addresses this challenge with IORM

47 IORM and DBRM Oracle DBRM allows managing CPU and other internal DB resources, e.g. parallelism, among compe3ng workloads in a single database DBRM is not Exadata Specific With Exadata IORM integra3on, IO resources are also controlled by DBRM A DBRM resource plan is also called an intra- database resource plan

48 IORM Plans Approaches for managing resource allocavons Intra- database resource plans manage mul3ple workloads in a single database If only one database on the Exadata machine, only an intra- database resource plan is needed Inter- database resource plans manage resources among mulvple databases on Exadata Specifies alloca3ons to databases, not consumer groups Category plans allow resource control across databases by the type of workload An IORM plan is the combina3on of an inter- database plan and a category plan

49 IORM and DBRM DBRM Example Database DBM OM OLTP Consumer group Other OLTP Consumer group Database XBM Online query Consumer group Repor3ng Consumer group Batch query Consumer group

50 IORM and DBRM Category Plan Example Database DBM OM OLTP Consumer group Other OLTP Consumer group Database XBM Online query Consumer group Interactive category Batch category Repor3ng Consumer group Batch query Consumer group

51 IORM Example All User IO = 100% Category Plan 70% Interactive 30% Batch Interdatabase Plan 40% XBM 60% DBM 40% XBM 60% DBM Intradatabase Plan 50% 30% 70% 20% 30% IORM Allocation DBM OM OLTP 26.25% DBM OTHER OLTP: 15.75% XBM: ONLINE QUERY 28.00% DBM: REPORTING 18.00% XBM: BATCH QUERY 12.00%

52 IORM Rules IORM is only engaged when needed LeIover disk alloca3on is made available to other workloads in rela3on to the configured resource plans max limits can be set Background IO is priori3zed rela3ve to user IO Redo and control file writes always take precedence DBWR writes are scheduled at the same priority as user IO If no intra- database plan is set, all non- background IO requests are grouped into the default OTHER_GROUPS consumer group

53 IORM Plan Syntax IORM plans created using CELLCLI / DCLI

54 IORM Monitoring IORM Metrics using CELLCLI / DCLI Metric Name DB_IO_RQ_SM DB_IO_RQ_LG DB_IO_RQ_SM_SEC DB_IO_RQ_LG_SEC DB_IO_WT_SM DB_IO_WT_LG Meaning Total number of IO requests issues by the database since any resource plan was set IO requests per second issued by the database in the last minute Total number of seconds that IO requests issued by the database waited to be scheduled Metric IORM script See Oracle Support Note: Tool for Gathering I/O Resource Manager Metrics: metric_iorm.pl [ID ] OEM (Grid Control) Exadata plugin

55 IORM Unless you only have one database with a single type of workload on Exadata then you should use IORM In other words Everyone using Exadata should use IORM!

56 IORM Benefits EDW for Large Organiza3on in Salt Lake valley 3.5 days before and aier enabling IORM/DBRM plans

57 Avoid the 3X Club Tune for Smart Scans Wisely use Parallelism Compress with HCC where appropriate Invoke Resource Management (IORM) S3ll follow Data Warehouse Best Prac3ces

58 Follow DW Best Prac3ces Oracle data warehousing on Exadata is s3ll data warehousing on Oracle (With a few incredible innova3ons J ) So Data Warehouse Best Prac3ces s3ll apply!

59 Follow DW Best Prac3ces Key Best PracVces Dimensional Model (Star Schema) Well- wrimen SQL Table Par33oning (par3cularly fact tables) Par33on by load frequency, sub par33on by join hash Par33on Exchange loading Parallel, Direct- Path (possibly nolog) Data Loading Including Constraint and Index management Query Rewrite Materialized Views and OLAP cubes Star Transforma3on Joins

60 GeAng the Most Out of Your Exadata DW Smart Scans (Storage Offloading) Parallelism DW Best PracVces Hybrid Columnar Compression

61 Ques3ons?