Discovering the plan cache (sql sat175)

1. Jason Strate Database Architect Pragmatic Works, Inc. DISCOVERING THE PLAN CACHE SQL SATURDAY 175 FARGO

2. Session Goals Viewing The Plan Cache Showplan XML Structure Scenarios and Demos Wrap Up SESSION AGENDA

3. SESSION GOALS Wrap Up Scenarios and Demos Showplan XML Structure Viewing The Plan Cache Session Goals

4. 1. Discuss the plan cache 2. Explore the plan cache 3. Demonstrate methods to query plan cache 4. Demonstrate performance tuning concepts SESSION GOALS

5. SQL Server 2012 SQL Server 2008 (R2) SQL Server 2005 CONTENT COMPATIBILITY

6. VIEWING THE PLAN CACHE Wrap Up Scenarios and Demos Showplan XML Structure Viewing The Plan Cache Session Goals

7. Portion of SQL Server memory that stores execution plans that have been prepared by the Query Optimizer. Execution plans are used to by SQL Server to execute SQL statements. PLAN CACHE

8. Pros No setup Query-able Actionable Real World Cons Reset with service Activity flush Plans miss cache In Use PLAN CACHE Portion of SQL Server memory that stores execution plans that have been prepared by the Query Optimizer. Execution plans are used to by SQL Server to execute SQL statements.

9.  sys.dm_exec_cached_plans • All Plans • Size • Use count  sys.dm_exec_query_plan (plan_handle) • Table Valued Function • SHOWPLAN XML as XML  sys.dm_exec_text_query_plan (plan_handle,0,-1) • Table Valued Function • SHOWPLAN XML as text PLAN CACHE

10. 0x06000F001CF36A2640C1318A… Varbinary(64) Hash value Identifies plan PLAN HANDLE

11. sys.dm_exec_requests Current connection Vaguely similar to sp_who sys.dm_exec_query_stats Stats on executed queries Contains SQL_Handle sys.dm_exec_cached_plans Stats on cached plans Distinct list of plans WHERE IN THE WORLD IS PLAN_HANDLE? http://www.flickr.com/photos/fallentomato/3918329246/

12. SHOWPLAN XML STRUCTURE Wrap Up Scenarios and Demos Showplan XML Structure Viewing The Plan Cache Session Goals

13. DBA-409-S GETTING STARTED

17. DBA-409-S EXECUTION PLAN

18. DBA-409-S SHOWPLAN XML STRUCTURE

19. What is in it? SHOWPLAN XML STRUCTURE http://www.flickr.com/photos/etringita/854298772/ ShowPlanXML BatchSequence Batch Statements StmtSimple

20. GOING BELOW STMTSIMPLE Missing Indexes •Indexes that would improve plan performance Parameter List •Parameters passed into query Warnings •Plan Affecting Convert •Columns with no Statistics •Unmatched Indexes RelOp •EstimateRows, EstimateIO, PhysicalOp, •Hash, IndexScan, NestedLoops •OutputList

21. Volatile Data Cache In Use Use Xquery Be Mindful CAUTION

22. • Forward slashes  / means to find the specific location  // means find any from the current location • Important Functions • nodes() • value() • exist() • query() • Everything is case sensitive XQUERY FUNCTIONS

23. SCENARIOS AND DEMOS Wrap Up Scenarios and Demos Showplan XML Structure Viewing The Plan Cache Session Goals

24. What plans would benefit from indexes? DMVs  sys.dm_db_missing_index_columns  sys.dm_db_missing_index_details  sys.dm_db_missing_index_group_stats  sys.dm_db_missing_index_groups DBA-409-S MISSING INDEXES

25. What plans would benefit from indexes? DMVs  sys.dm_db_missing_index_columns  sys.dm_db_missing_index_details  sys.dm_db_missing_index_group_stats  sys.dm_db_missing_index_groups MISSING INDEXES http://www.flickr.com/photos/fallentomato/3918329246/ What Queries Should I Test?

26. Demo 1MISSING INDEXES

27. Data types matter? varchar vs. nvarchar scan vs. seek What plans have this issue? CONVERSION WARNINGS Here lies your transaction

28. Columns with no Statistics Unmatched Indexes Spill to Tempdb* OTHER WARNINGS

29. Demo 2 IMPLICIT CONVERSIONS AND OTHER WARNINGS

30. Think about the plans you find example… What has changed in the environments? Is the plan using the wrong values? What parameters is the plan using? POOR PARAMETER SNIFFING

31. Demo 3 PARAMETER SNIFFING

32. What’s the parallelism trigger? • Parallelism is cost based • Query cost default 5 STATEMENT INFORMATION

33. What does SQL Server expect? • CPU • IO • Rows • Cost QUERY TREE ESTIMATES

34. Demo 3QUERY PROPERTIES

35. LET’S GET PHYSICAL

36. Demo 5PHYSICAL OPERATIONS

37.  Access Methods:Full Scans/sec INDEX OPERATIONS

38.  Access Methods:Full Scans/sec INDEX OPERATIONS

39. What about large tables? Scans?  Good?  Bad? What do you do when you see large counts of scans on an index? INDEX OPERATIONS

40. What plans are using that index? Should you drop it? What is the potential effect? INDEX OPERATIONS http://www.flickr.com/photos/s3a/4436302537/

41. Demo 5INDEX OPERATIONS

42. Find value in one index Look up more columns in clustered index KEY LOOKUP

43. You found them… NOW fix them… The information is in the plan! • Investigate the nodes • Pull in the data! DEEPER FOR INCLUDED INDEXES

44. Demo 4 KEY LOOKUPS & INCLUDED COLUMNS

45. WRAP UP Wrap Up Scenarios and Demos Showplan XML Structure Viewing The Plan Cache Session Goals

46.  http://schemas.microsoft.com/sqlserver  /2004/07/showplan/showplanxml.xsd FIND YOUR OWN TREASURE

47. 1. Plan Cache IS your performance work load 2. Information is readily available 3. Techniques to access not as complex as appearances 4. Scale your performance knowledge across the environment SUMMARY

48.  www.operationsmile.org  www.manning.com/delaney SQL SERVER MVP DEEP DIVES, VOLUME 2

49. Jason Strate e: jstrate@pragmaticworks.com e: jasonstrate@gmail.com b: www.jasonstrate.com t: StrateSQL Resources jasonstrate.com/go/Cache2013 RESOURCES

Discovering the plan cache (sql sat175)

Discovering the plan cache (sql sat175)

Recomendados

Más contenido relacionado

Destacado

Destacado(20)

Similar a Discovering the plan cache (sql sat175)

Similar a Discovering the plan cache (sql sat175)(20)

Más de Jason Strate

Más de Jason Strate(19)

Discovering the plan cache (sql sat175)