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132 lines
3.6 KiB
Transact-SQL
132 lines
3.6 KiB
Transact-SQL
-- ************************************************************************ --
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-- Query Store hints demo
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-- Demo uses "PropertyMLS" database which can be imported from BACPAC here:
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-- https://github.com/microsoft/sql-server-samples/tree/master/samples/features/query-store
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-- Email QSHintsFeedback@microsoft.com for questions\feedback
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-- ************************************************************************ --
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/*
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Demo prep, connect to the PropertyMLS database
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*/
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ALTER DATABASE [PropertyMLS] SET QUERY_STORE CLEAR;
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ALTER DATABASE CURRENT SET QUERY_STORE = ON;
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ALTER DATABASE CURRENT SET QUERY_STORE (QUERY_CAPTURE_MODE = ALL);
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GO
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-- Should be READ_WRITE
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SELECT actual_state_desc
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FROM sys.database_query_store_options;
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GO
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/*
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You can verify Query Store Hints in sys.query_store_query_hints.
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Checking if any already exist (should be none).
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*/
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SELECT query_hint_id,
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query_id,
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query_hint_text,
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last_query_hint_failure_reason,
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last_query_hint_failure_reason_desc,
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query_hint_failure_count,
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source,
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source_desc
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FROM sys.query_store_query_hints;
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GO
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/*
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The PropertySearchByAgent stored procedure has a parameter
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used to filter AgentId. Looking at the statistics for AgentId,
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you will see that there is a big skew for AgentId 101.
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*/
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SELECT hist.range_high_key AS [AgentId],
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hist.equal_rows
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FROM sys.stats AS s
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CROSS APPLY sys.dm_db_stats_histogram(s.[object_id], s.stats_id) AS hist
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WHERE s.[name] = N'NCI_Property_AgentId';
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-- Show actual query execution plan to see plan compiled.
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-- Agent with many properties will have a scan with parallelism.
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EXEC [dbo].[PropertySearchByAgent] 101;
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-- Agents with few properties still re-use this plan (assuming no recent plan eviction).
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EXEC [dbo].[PropertySearchByAgent] 4;
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/*
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Now let's find the query_id associated with this query.
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*/
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SELECT query_sql_text, q.query_id
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FROM sys.query_store_query_text qt
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INNER JOIN sys.query_store_query q ON
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qt.query_text_id = q.query_text_id
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WHERE query_sql_text like N'%ORDER BY ListingPrice DESC%' and query_sql_text not like N'%query_store%';
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GO
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/*
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We can set the hint associated with the query_id returned in the previous result set, as below.
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Note, we can designate one or more query hints
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*/
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EXEC sp_query_store_set_hints @query_id=5, @value = N'OPTION(RECOMPILE)';
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GO
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/*
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You can verify Query Store Hints in sys.query_store_query_hints
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*/
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SELECT query_hint_id,
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query_id,
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query_hint_text,
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last_query_hint_failure_reason,
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last_query_hint_failure_reason_desc,
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query_hint_failure_count,
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source,
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source_desc
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FROM sys.query_store_query_hints;
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GO
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-- Execute both at the same time and show actual query execution plan.
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-- You should see two different plans, one for AgentId 101 and one for AgentId 4.
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EXEC [dbo].[PropertySearchByAgent] 101;
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EXEC [dbo].[PropertySearchByAgent] 4;
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GO
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SELECT query_hint_id,
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query_id,
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query_hint_text,
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last_query_hint_failure_reason,
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last_query_hint_failure_reason_desc,
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query_hint_failure_count,
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source,
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source_desc
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FROM sys.query_store_query_hints;
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GO
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/*
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We can remove the hint using sp_query_store_clear_query_hints
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*/
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EXEC sp_query_store_clear_hints @query_id = 10;
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GO
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/*
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That Query Store Hint is now removed
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*/
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SELECT query_hint_id,
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query_id,
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query_hint_text,
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last_query_hint_failure_reason,
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last_query_hint_failure_reason_desc,
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query_hint_failure_count,
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source,
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source_desc
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FROM sys.query_store_query_hints;
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GO
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-- Execute both at the same time and show actual query execution plan.
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-- You should see one plan again.
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EXEC [dbo].[PropertySearchByAgent] 101;
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EXEC [dbo].[PropertySearchByAgent] 4;
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GO
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