DBA - How to find CPU intensive queries

 -- Clear the query plan cache (don't execute this in production!)

dbcc freeproccache

go

 

-- CPU intensive query over adventureworks database

select TransactionId,ProductId,

             ReferenceOrderId,ReferenceOrderLineId,

             TransactionDate,TransactionType,

             Quantity,ActualCost,

             ModifiedDate

from production.TransactionHistory

       order by modifiedDate desc

Now, let’s check the most cpu intensive queries in our system:

SELECT

       -- using statement_start_offset and

       -- statement_end_offset we get the query text

       -- from inside the entire batch

       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)

                           as [Text],

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,

-- converting microseconds to seconds

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

FROM sys.dm_exec_query_stats qs

       -- Retrieve the query text

       CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt

       -- Retrieve the query plan

       CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp

ORDER BY qs.total_worker_time DESC -- CPU time