This document summarizes tools that can be used to analyze query performance in SQL Server. It discusses the query optimizer, SQL Trace, SQL Server Profiler, Extended Events, SET session options, dynamic management objects, and execution plans. The query optimizer uses cost-based optimization and cardinality estimation. SQL Trace and Profiler are easy to use but produce overhead. Extended Events provide a more efficient alternative. Dynamic management objects and SET options provide insight into query execution. Execution plans show the optimizer's estimated plan and the actual plan used.

1. Polish SQL Server User Group
Using Tools to
Analyze Query Performance
CHAPTER 14

2. Polish SQL Server User Group
About the Author
Marek Maśko
• Principal Database Analyst at Sabre
• Working with SQL Server since 2010
• SQL DBA, Dev & Architect
• MCP since 2012
• Contact Information:
Email: marek.masko@gmail.com
LinkedIn: https://pl.linkedin.com/in/marekmasko
Twitter: @MarekMasko

3. Polish SQL Server User Group
Agenda
• Query Optimizer
• SQL Trace
• SQL Server Profiler
• SQL Server Extended Events
• SET Session Options
• Dynamic Management Objects
• Execution Plans

4. Polish SQL Server User Group
QUERY OPTIMIZER

5. Polish SQL Server User Group
Query Performance
• Time
• CPU
• Memory
• I/O

6. Polish SQL Server User Group
Query Optimization
Relational Engine
T-SQL
Statement Parser Algebrizer
Query
Optimizer
Storage Engine
Query
Parsing
Parse
Tree
Normalization
and Binding
Query
Processor
Tree
Query
Optimization
Execution
Plan

7. Polish SQL Server User Group
Query Optimizer
• Cost based
• Cardinality Estimation

8. Polish SQL Server User Group
SQL TRACE &
SQL SERVER PROFILER

9. Polish SQL Server User Group
SQL Trace & Profiler
https://msdn.microsoft.com/en-us/library/hh245121.aspx

10. Polish SQL Server User Group
Benefits and drawbacks
• Easy to use
• Produces overhead:
–Local resources
–Network
• Results grid can consume a lot of memory
• Deprecated!

11. Polish SQL Server User Group
SQL SERVER EXTENDED EVENTS

12. Polish SQL Server User Group
Extended Events Engine
https://technet.microsoft.com/en-us/library/dd822788(v=sql.100).aspx

13. Polish SQL Server User Group
Extended Events Engine
https://technet.microsoft.com/en-us/library/dd822788(v=sql.100).aspx

14. Polish SQL Server User Group
SET SESSION OPTIONS

15. Polish SQL Server User Group
SET Session Options
• SET STATISTICS IO
• SET STATISTICS TIME

16. Polish SQL Server User Group
DYNAMIC MANAGEMENT OBJECTS

17. Polish SQL Server User Group
DMO
• System views and functions
• More than 130
• Exist in sys system schema
• Names start with dm_
• Shows current state or
data cumulated from instance start

18. Polish SQL Server User Group
DMO
• SQLOS related
• Execution related
• Index related

19. Polish SQL Server User Group
Most Important DMOs
• dm_exec_requests
• dm_exec_sessions
• dm_exec_sql_text()
• dm_exec_query_stats
• dm_os_wait_stats
• dm_os_waiting_tasks
• dm_db_missing_index_details
• dm_db_missing_index_columns
• dm_db_missing_index_groups
• dm_db_missing_index_group_stats

20. Polish SQL Server User Group
EXECUTION PLANS

21. Polish SQL Server User Group
Estimated and Actual Execution Plans
Estimated execution plan
• Output from the Optimizer
• Query doesn’t have to be executed
• Tells you what SQL Server would most likely do
• Stored in the plan cache
Actual execution plan
• Output from the actual query execution
• Tells you exactly what SQL Server did

22. Polish SQL Server User Group
Execution Plan Formats
• Graphical Plans
• Text Plans
• XML Plans

23. Polish SQL Server User Group
Graphical Plan

24. Polish SQL Server User Group
Text Plan

25. Polish SQL Server User Group
XML Plan

26. Polish SQL Server User Group
SET Session Options
• Text plans
–SET SHOWPLAN_TEXT and SET SHOWPLAN_ALL for
estimated plans
–SET STATISTICS PROFILE for actual plans
• XML plans
–SET SHOWPLAN_XML for estimated plans
–SET STATISTICS XML for actual plans

27. Polish SQL Server User Group
THANK YOU!

28. Polish SQL Server User Group
Resources
• Book: Training Kit Exam 70-461
• Scripts for Training Kit