MS SQL Server – Log slow queries

source: http://blog.brianhartsock.com/2008/12/16/quick-and-dirty-sql-server-slow-query-log/

This query will list the top 20 most read intensive queries. What is great is it is based on total reads, so it is a quick and dirty way to find the worst queries in your system. Eliminating the top few queries on this list will give you the best bang for your buck.

Note that this query requires SQL Server 2005 or newer with the database running in compatibility mode 90 or higher. Otherwise, it throws a syntax error after the CROSS APPLY.

SELECT TOP 20 SUBSTRING(qt.text, (qs.statement_start_offset/2)+1, 
        ((CASE qs.statement_end_offset
          WHEN -1 THEN DATALENGTH(qt.text)
         ELSE qs.statement_end_offset
         END - qs.statement_start_offset)/2)+1), 
qs.execution_count, 
qs.total_logical_reads, qs.last_logical_reads,
qs.min_logical_reads, qs.max_logical_reads,
qs.total_elapsed_time, qs.last_elapsed_time,
qs.min_elapsed_time, qs.max_elapsed_time,
qs.last_execution_time,
qp.query_plan
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
WHERE qt.encrypted=0
ORDER BY qs.total_logical_reads DESC

Alternative version

/*Debug query */
SELECT TOP 100
qt.text as QUERY,
qs.execution_count,
qs.total_logical_reads, qs.last_logical_reads,
qs.min_logical_reads, qs.max_logical_reads,
qs.total_elapsed_time, qs.last_elapsed_time,
qs.min_elapsed_time, qs.max_elapsed_time,
qs.last_execution_time,
qp.query_plan
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
WHERE qt.encrypted=0
and qt.text not like ‘/*Debug query */%’
ORDER BY qs.last_execution_time DESC, qs.total_logical_reads DESC