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Friday, 9 January 2015

Optimization Techniques- Finding Most expensive Queries in Sql Server

Following query will help you finding the most expensive queries in your sql database. This query will tell you about Total Logical Reads, Total Logical Writes, Last Logical Reads, Last Logical Writes etc.
Run the following query in your sql server query window:

SELECT TOP 10 qs.execution_count
        ,qs.total_logical_reads
        ,qs.last_logical_reads
        ,qs.total_logical_writes
        ,qs.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_plan
        ,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)
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
ORDER BY qs.total_worker_time DESC -- CPU time