11Mar 2019 by Grant Fritchey 4 Comments

Missing Indexes in the Query Store

SQL Server 2016, SQL Server 2017, T-SQL, Tools
I've shown before how to use the DMVs that read the plan cache as a way to connect the missing indexes suggestions with specific queries, but the other place to find missing index suggestions is the Query Store. Pulling from the Query Store The plans stored in the Query Store are exactly the same as the plans stored within the plan cache. This means that the XML is available and you can try to retrieve information from it directly, just as we did with the missing index queries against the DMVs. Here's the query modified for the Query Store: WITH XMLNAMESPACES (DEFAULT 'http://schemas.microsoft.com/sqlserver/2004/07/showplan') SELECT qsqt.query_sql_text, rts.plan_id, rts.NumExecutions, rts.MinDuration, rts.MaxDuration, rts.AvgDuration, rts.AvgReads, rts.AvgWrites, qsp.QueryPlan, qsp.QueryPlan.value(N'(//MissingIndex/@Table)[1]', 'NVARCHAR(256)') AS TableName, qsp.QueryPlan.value(N'(//MissingIndex/@Schema)[1]', 'NVARCHAR(256)') AS SchemaName, qsp.QueryPlan.value(N'(//MissingIndexGroup/@Impact)[1]', 'DECIMAL(6,4)') AS ProjectedImpact, ColumnGroup.value('./@Usage', 'NVARCHAR(256)') AS ColumnGroupUsage, ColumnGroupColumn.value('./@Name',…
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06Dec 2010 by Grant Fritchey 12 Comments

Review: Idera SQL Doctor

SQL Server, T-SQL, Tools
Recently, a co-worker practically slammed me up against the wall, exclaiming “You have to check out this new tool, right now!” The piece of software he was so excited about was Idera’s SQL Doctor. Based on this assaultrecommendation, I decided to take a little time & look the software over. SQL Doctor, as the name implies, is a diagnostic tool. It runs a set of best practice rules against your server, your databases and your code. As the rules are executed, your system’s compliance with these best practices is evaluated and an interactive report is generated. With the report you can drill down on various aspects of your system to see where you may have gone wrong. All that sounds very clinical, just laid out like that. But the fact…
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02Mar 2009 by Grant Fritchey 9 Comments

More Refinements on the Missing Indexes Query

SQL Server, T-SQL
Greg Larson posted a really nice query to find worst performing stored procedures in your system. He put in all kinds of attributes to make it customizable, changing the definition of "worst" to different measures,etc. Great query in general. In it he linked to sys.dm_exec_plan_attributes and got the db_id attribute. Duh! So instead of spelunking through the XML to retrieve the database name, I can pull the db_id and use the DB_NAME function. Cleans things up considerably. Thanks Greg. Here's the cleaned up code: WITH XMLNAMESPACES ('http://schemas.microsoft.com/sqlserver/2004/07/showplan' AS sp) SELECT DB_NAME(CAST(pa.value AS INT)) ,s.sql_handle ,s.total_elapsed_time ,s.last_execution_time ,s.execution_count ,s.total_logical_writes ,s.total_logical_reads ,s.min_elapsed_time ,s.max_elapsed_time --,s.query_hash ,p.query_plan ,p.query_plan.value(N'(sp:ShowPlanXML/sp:BatchSequence/sp:Batch/sp:Statements/sp:StmtSimple/sp:QueryPlan/sp:MissingIndexes/sp:MissingIndexGroup/sp:MissingIndex/@Table)[1]', 'NVARCHAR(256)') AS TableName ,p.query_plan.value(N'(/sp:ShowPlanXML/sp:BatchSequence/sp:Batch/sp:Statements/sp:StmtSimple/sp:QueryPlan/sp:MissingIndexes/sp:MissingIndexGroup/sp:MissingIndex/@Schema)[1]', 'NVARCHAR(256)') AS SchemaName ,p.query_plan.value(N'(/sp:ShowPlanXML/sp:BatchSequence/sp:Batch/sp:Statements/sp:StmtSimple/sp:QueryPlan/sp:MissingIndexes/sp:MissingIndexGroup/@Impact)[1]', 'DECIMAL(6,4)') AS ProjectedImpact ,ColumnGroup.value('./@Usage', 'NVARCHAR(256)') AS ColumnGroupUsage ,ColumnGroupColumn.value('./@Name', 'NVARCHAR(256)') AS ColumnName FROM (SELECT TOP 20 s.sql_handle ,s.plan_handle ,s.total_elapsed_time…
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18Feb 2009 by Grant Fritchey 24 Comments

Refining the Missing Index Data

SQL Server, T-SQL
In my previous post I showed how you could determine if a query had missing index information, but it was difficult to get meaningful data out because I didn't know XQuery well enough. I spent some more time refining the query and here are the results. This new query will show some basic performance information gathered from the aggregate data in sys.dm_exec_query_stats. It combines this with the full data pulled from the Missing Indexes element in the XML of the execution plan. I've got it listing all the recommended columns and grouping. So this means that the performance data is repeated in order to allow for the full listing of groups & columns. It seems to work well. A couple of interesting points. My purpose is to provide a short-cut…
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