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SQL Server 2016 Query store

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SQL Server 2016 Query store

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SQL Server 2016 Query store

  1. 1. SQL Server Query Store Vitaliy Popovych
  2. 2. About me • Vitaliy Popovych • Database Developer at Intapp
  3. 3. Agenda • Query Store • How it works • Configuration Options • UI Management Studio • Query Store Catalog Views • Query Store Stored Procedures • Best Practice with the Query Store • Demo
  4. 4. Recompiling Execution Plans • Changes made to a table or view referenced by the query (ALTER TABLE and ALTER VIEW). • Changes made to a single procedure, which would drop all plans for that procedure from the cache (ALTER PROCEDURE). • Changes to any indexes used by the execution plan. • Updates on statistics used by the execution plan, generated either explicitly from a statement, such as UPDATE STATISTICS, or generated automatically. • Dropping an index used by the execution plan. • An explicit call to sp_recompile. • Large numbers of changes to keys (generated by INSERT or DELETE statements from other users that modify a table referenced by the query). • For tables with triggers, if the number of rows in the inserted or deleted tables grows significantly. • Executing a stored procedure using the WITH RECOMPILE option.
  5. 5. What is Query Store?
  6. 6. Query Store Compile Execute Plan Store Runtime Stats Query Store Schema
  7. 7. How to start
  8. 8. Common scenarios • Quickly find and fix a plan performance regression by forcing the previous query plan. Fix queries that have recently regressed in performance due to execution plan changes. • Determine the number of times a query was executed in a given time window, assisting a DBA in troubleshooting performance resource problems. • Identify top n queries (by execution time, memory consumption, etc.) in the past x hours. • Audit the history of query plans for a given query. • Analyze the resource (CPU, I/O, and Memory) usage patterns for a particular database.
  9. 9. Enable Query Store By Using Transact-SQL Statements ALTER DATABASE [AdventureWorks2016CTP3] SET QUERY_STORE = ON ( CLEANUP_POLICY = (STALE_QUERY_THRESHOLD_DAYS = 31), DATA_FLUSH_INTERVAL_SECONDS = 900, INTERVAL_LENGTH_MINUTES = 5, MAX_STORAGE_SIZE_MB = 1024, QUERY_CAPTURE_MODE = ALL, SIZE_BASED_CLEANUP_MODE = AUTO ) GO By Using the Query Store Page in Management Studio - In the Database Properties dialog box, select the Query Store page. - In the Enable box, select True.
  10. 10. Configuration Options  OPERATION_MODE  CLEANUP_POLICY  DATA_FLUSH_INTERVAL_SECONDS  MAX_STORAGE_SIZE_MB  INTERVAL_LENGTH_MINUTES  SIZE_BASED_CLEANUP_MODE  MAX_PLANS_PER_QUERY
  11. 11. Configuration Options MAX_STORAGE_SIZE_MB (Configures the maximum size of the query store. If the data in the query store hits the MAX_STORAGE_SIZE_MB limit, the query store automatically changes the state from read-write to read-only and stops collecting new data) default value = 100 MB OPERATION_MODE (Can be READ_WRITE or READ_ONLY) default value = READ_WRITE CLEANUP_POLICY (Configure the STALE_QUERY_THRESHOLD_DAYS argument to specify the number of days to retain data in the query store) default value = 367 days
  12. 12. Configuration Options DATA_FLUSH_INTERVAL_SECONDS (Determines the frequency at which data written to the query store is persisted to disk. To optimize for performance, data collected by the query store is asynchronously written to the disk. The frequency at which this asynchronous transfer occurs is configured via DATA_FLUSH_INTERVAL_SECONDS) default value = 900 sec INTERVAL_LENGTH_MINUTES (Determines the time interval at which runtime execution statistics data is aggregated into the query store. To optimize for space usage, the runtime execution statistics in the Runtime Stats Store are aggregated over a fixed time window. This fixed time window is configured via INTERVAL_LENGTH_MINUTES) default value = 60 min
  13. 13. Configuration Options QUERY_CAPTURE_MODE (Designates if the Query Store captures all queries, or relevant queries based on execution count and resource consumption, or stops adding new queries and just tracks current queries) default value = all MAX_PLANS_PER_QUERY (An integer representing the maximum number of plans maintained for each query) default value = 200 SIZE_BASED_CLEANUP_MODE (Controls whether the cleanup process will be automatically activated when total amount of data gets close to maximum size) default value = OFF
  14. 14. Information Execution metric Statistic function CPU time, Duration, Execution Count, Logical Reads, Logical writes, Memory consumption, Physical Reads Average, Maximum, Minimum, Standard Deviation, Total
  15. 15. UI Management Studio Regressed Queries (Pinpoint queries for which execution metrics have recently regressed i.e. changed to worse) Overall Resource Consumption (Analyze the total resource consumption for the database for any of the execution metrics) Top Resource Consuming Queries (Queries which have the biggest impact to database resource consumption) Tracked Queries (Track the execution of the most important queries in real-time)
  16. 16. Regressed Queries Pinpoint queries for which execution metrics have recently regressed (i.e. changed to worse). Use this view to correlate observed performance problems in your application with the actual queries that needs to be fixed or improved.
  17. 17. Overall Resource Consumption Analyze the total resource consumption for the database for any of the execution metrics. Use this view to identify resource patterns (daily vs. nightly workloads) and optimize overall consumption for your database.
  18. 18. Top Resource Consuming Queries Choose an execution metric of interest and identify queries that had the most extreme values for a provided time interval. Use this view to focus your attention on the most relevant queries which have the biggest impact to database resource consumption.
  19. 19. Tracked Queries Track the execution of the most important queries in real-time. Typically, you use this view when you have queries with forced plans and you want to make sure that query performance is stable.
  20. 20. Query Store Catalog Views • sys.database_query_store_options (Returns the Query Store options for this database) • sys.query_store_plan (Contains information about each execution plan associated with a query) • sys.query_store_query (Contains information about the query and aggregated runtime execution statistics) • sys.query_store_query_text (Contains the Transact-SQL text and the SQL handle of the query) • sys.query_store_runtime_stats (Contains information about the runtime execution statistics information for the query) • sys.query_store_runtime_stats_interval (Contains information about the start and end)
  21. 21. Query Store Stored Procedures • sp_query_store_flush_db (Flushes the in-memory portion of the Query Store data to disk) • sp_query_store_force_plan (Enables forcing a particular plan for a particular query) • sp_query_store_remove_plan (Removes a single plan from the query store) • sp_query_store_remove_query (Removes the query, as well as all associated plans and runtime stats from the query store) • sp_query_store_reset_exec_stats (Clears the runtime stats for a specific query plan from the query store) • sp_query_store_unforce_plan (Enables unforcing a particular plan for a particular query)
  22. 22. Best Practice with the Query Store • Use the Latest SQL Server Management Studio • Keep Query Store Adjusted to your Workload • Verify Query Store is Collecting Query Data Continuously • Set the Optimal Query Capture Mode • Keep the Most Relevant Data in Query Store • Avoid Using Non-Parameterized Queries • Check the Status of Forced Plans Regularly
  23. 23. Demo
  24. 24. Resources • SQLServer Blog • MSDN • A flight data recorder for your database (Borko Novakovic) • The SQL Server Query Store (Benjamin Nevarez)
  25. 25. Question?
  26. 26. Thanks! Vitaliy Popovych E-mail: vitaliy.popovych@outlook.com

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