Friday, 20 February 2015

SQL SERVER – Find Most Expensive Queries Using DMV


The title of this post is what I can express here for this quick blog post. I was asked in recent query tuning consultation project, if I can share my script which I use to figure out which is the most expensive queries are running on SQL Server. This script is very basic and very simple, there are many different versions are available online. This basic script does do the job which I expect to do – find out the most expensive queries on SQL Server Box.
SELECT TOP 10 SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1,
((
CASE qs.statement_end_offsetWHEN -THEN DATALENGTH(qt.TEXT)ELSE qs.statement_end_offsetEND qs.statement_start_offset)/2)+1),qs.execution_count,qs.total_logical_readsqs.last_logical_reads,qs.total_logical_writesqs.last_logical_writes,qs.total_worker_time,qs.last_worker_time,qs.total_elapsed_time/1000000 total_elapsed_time_in_S,qs.last_elapsed_time/1000000 last_elapsed_time_in_S,qs.last_execution_time,qp.query_planFROM sys.dm_exec_query_stats qsCROSS APPLY sys.dm_exec_sql_text(qs.sql_handleqtCROSS APPLY sys.dm_exec_query_plan(qs.plan_handleqpORDER BY qs.total_logical_reads DESC -- logical reads
-- ORDER BY qs.total_logical_writes DESC -- logical writes
-- ORDER BY qs.total_worker_time DESC -- CPU time
You can change the ORDER BY clause to order this table with different parameters. I invite my reader to share their scripts.

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