Geek Sync | Intro to Query Store
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The document provides an overview of SQL Server Query Store, including what it can do, how to set it up, how it works, available reports, usage scenarios, features in 2017 and later versions, troubleshooting, and best practices. Query Store collects query execution plans and runtime statistics to help identify regressions, top resource consumers, and wait stats. It can automatically correct plans and supports forcing historical plans. Reports provide insights on regressed queries, resource usage, and wait stats. Query Store is enabled per database and supports various configuration options.
![Query Store Setup
• Run one simple command:
• ALTER DATABASE [DatabaseName]
SET QUERY_STORE = ON;](https://image.slidesharecdn.com/idera-geeksync-query-store-200923160301/85/Geek-Sync-Intro-to-Query-Store-8-320.jpg)
Geek Sync | Intro to Query Store
- 1. Intro to Query Store By Tracy Boggiano
- 2. Tracy Boggiano SQL Server DBA for 20+ years @TracyBoggiano databasesuperhero.com tracyboggiano speakingmentors.com
- 3. • What It Can Do For Us? • Setup • How It Works • Reports • Usage Scenarios • 2017 Features • Troubleshooting • Best Practices Agenda
- 4. WHAT IT CAN DO FOR US?
- 5. What Query Store Can Do For Us? • Regressed Queries • Identify Top Consuming Queries • Audit the history of query plans • Identify Resource Consumption Patterns
- 6. What Query Store Can Do For Us? • In 2017 • Wait Stats • Automatic plan correction • Show more statistics • In 2019 • Show even more statistics
- 7. SETUP
- 8. Query Store Setup • Run one simple command: • ALTER DATABASE [DatabaseName] SET QUERY_STORE = ON;
- 9. Query Store Options 2016+ • Operation Mode • Data Flush Interval (Minutes) • Statistics Collection Interval • Max Size (MB) • Query Store Capture Mode • Size Based Cleanup Mode • Stale Query Threshold (Days)
- 10. Query Store Options 2017 • Waits Statistics Capture • Max Plans Per Query
- 11. Query Store Options 2019 • Query Store Capture Mode = CUSTOM Stale Capture Policy Threshold Execution Count Total Compile CPU Time MS Total Execution CPU Time MS
- 12. Query Store Setup • PRIMARY filegroup • https://feedback.azure.com/forums/90803 5-sql-server/suggestions/32902072- option-to-store-query-store-data-in-a- filegroup-ot
- 13. Query Store Setup • Per Database • Nice to have Central Repository • https://feedback.azure.com/forums/9 08035-sql- server/suggestions/33815995-create- central-repository-for-query-store
- 14. Query Store Trace Flags • 7745 - Forces Query Store to not flush data to disk on database shutdown. • 7752 - Enables asynchronous loading of database
- 15. GUI • Right click the database, the click on properties, then Query Store
- 16. dbatools • Get-DbaQueryStoreOptions • Set-DbaQueryStoreOptions • Copy-DbaQueryStoreOptions
- 17. Query Store Setup Summary • Set your options especially size • PRIMARY filegroup • Per database • Use CUSTOM if you have ad-hoc quereies and are on 2019
- 18. HOW IT WORKS
- 19. How Query Store Collects Information • Query processed by Algebrizer and sends it to the Query Optimizer • Checks for forced plan or out pops a new Execution Plan • Query Plan is put into Plan Cache • Async collects data into Query Store Memory • Async writes to disk
- 20. Where Query Store Collects Information • Plan Store – query plan, query text, last execution time, compile time • Runtime Stats Store – all runtime stats for plans, cpu, logical reads, logical writes, physical reads, memory, tempdb, duration, execution count • Wait Stats Store – wait categories per plan
- 22. Ways to Stabilize Perfomance • Change code and/or schema • Add RECOMPILE • Manually get the best plan in the cache • Use a plan guide • Force a plan using query store
- 23. Regressed Queries • Identify queries that have degraded in performance • See if there is plan that can be forced easily • Force the previous plan from the history
- 26. Check Status of Forced Queries • Query = is_forced_plan = 1 • Look at report in SSMS • Extended event
- 28. Top Consuming Resources • Look at forcing a plan because of regression • Missing indexes • Make sure that the statistics are up-to-date • Make sure that indexes used by the query are defragmented • Consider rewriting expensive query
- 29. Queries with High Variation
- 31. Queries with Force Plans
- 32. REPORTS DEMO
- 33. USAGE SCENARIOS
- 34. Forcing Query Plans Manually • Using reports you can easily find queries with multiple plans and force a plan • They are not schema-bound • Should monitor for failures with Extended Events • When manually forced the plan is used even when it is no longer optimal
- 35. A/B Testing • Rolling out new application version • Adding new hardware to the server • Creating missing indexes for expensive queries
- 37. Summary of Usage Scenarios • Forcing Query Plans Manually • A/B testing • Upgrade SQL Server
- 38. Database Superhero 2018 2017 FEATURES
- 39. Wait Stats • New DMV sys.query_store_wait_stats • 23 categories • Tracks by category of wait stats such as CPU or MEMORY
- 40. Automatic Plan Correction • Recommendations surfaced via sys.dm_db_tuning_recommendations • Can automatically switch to last known good plan • Data is in DMV even if you don’t have the option turned on • Data is lost on reboot of SQL Server
- 41. Automatic Plan Correction Setup ALTER DATABASE CURRENT SET AUTOMATIC_TUNING (FORCE_LAST_GOOD_PLAN = ON);
- 42. Monitoring Automatic Plan Correction • Create an Extended Events session that captures automatic tuning events • automatic_tuning_error • automatic_tuning_plan_regression_detec tion_check_completed • automatic_tuning_plan_regression_verif ication_check_completed • automatic_tuning_recommendation_expire d
- 43. Summary of 2017 Features • Automatic Plan Correction • Wait Stats
- 45. TROUBLESHOOTING
- 46. Perfmon Counters • Query Store CPU usage • Query Store logical reads • Query Store logical writes • Query Store physical reads
- 48. Wait Stats • Ton of these, they all start with qds • Three can be safely ignored: • qds_async_queue • qds_cleanup_stale_queries_task_main_loop_sleep • qds_shutdown_queue • Use Paul Randal’s script is the best way to look at wait stats
- 49. Extended Events • Over 50 events added • Most can only be used by special trace flags for Microsoft troubleshooting • We will look at script for the important ones
- 50. BEST PRACTICES
- 51. Best Practices • Manage the size • Set you Statistics Interval • Make sure it is continuing to collect data • Avoid using non-parameterized queries • Avoid using drop/create process • Avoid renaming databases
- 52. Using the Query Store with In-Memory OLTP • Turn on runtime statistics collection with sys.sp_xtp_control_query_exec_stats • Need to reset on server restart or if you clear Query Store • Memory grants metrics are not kept
- 53. Things of Note • Forced plans can fail • Drop an index • Change the name of an index • Remove columns from an index • Forced plans for do work on the secondaries of your AGs • Forced plans don’t age out of Query Store
- 54. Resources • Monitoring Performance By Using the Query Store - https://docs.microsoft.com/en- us/sql/relational-databases/performance/monitoring-performance-by-using-the-query- store • Best Practice with the Query Store - https://msdn.microsoft.com/en- us/library/mt604821.aspx • Wait Stats - https://docs.microsoft.com/en-us/sql/relational-databases/system-catalog- views/sys-query-store-wait-stats-transact-sql • Automatic plan correction in SQL Server 2017 - https://blogs.msdn.microsoft.com/sqlserverstorageengine/2017/05/17/automatic-plan- correction-in-sql-server-2017/ • T-SQL Tuesday #124 Summary - https://tracyboggiano.com/archive/2020/03/t-sql- tuesday-124-query-store-summary/ • Erin Stellato’s Blog - https://www.sqlskills.com/blogs/erin/category/query-store/ • Grant Fritchey’s Blog - https://www.scarydba.com/?s=query+store