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Northglenn, Colorado, United States
I'm primarily a BI Developer on the Microsoft stack. I do sometimes touch upon other Microsoft stacks ( web development, application development, and sql server development).

Monday, November 28, 2011

SQL Server Query Performance Analysis

Great post by Carl Nolan(http://blogs.msdn.com/b/mcsuksoldev/archive/2011/11/27/adventure-in-tsql-sql-server-query-performance-analysis-using-dmvs.aspx) on finding the worst offending queries that do the most CPU and Disk I/O loads.

The two queries are:

CPU Query
-- Which Queries are taking the most time/cpu to execute
SELECT TOP 20
    total_worker_time
, total_elapsed_time,
    total_worker_time
/execution_count AS avg_cpu_cost, execution_count,
    
(SELECT DB_NAME(dbid) + ISNULL('..' + OBJECT_NAME(objectid), '')
        
FROM sys.dm_exec_sql_text([sql_handle])) AS query_database,
    
(SELECT SUBSTRING(est.[text], statement_start_offset/2 + 1,
        
(CASE WHEN statement_end_offset = -1
            
THEN LEN(CONVERT(nvarchar(max), est.[text])) * 2
            
ELSE statement_end_offset
            
END - statement_start_offset) / 2
        
)
        
FROM sys.dm_exec_sql_text([sql_handle]) AS est) AS query_text,
    total_logical_reads
/execution_count AS avg_logical_reads,
    total_logical_writes
/execution_count AS avg_logical_writes,
    last_worker_time
, min_worker_time, max_worker_time,
    last_elapsed_time
, min_elapsed_time, max_elapsed_time,
    plan_generation_num
, qp.query_plan
FROM sys.dm_exec_query_stats
    
OUTER APPLY sys.dm_exec_query_plan([plan_handle]) AS qp
WHERE [dbid] >= 5 AND DB_NAME(dbid) IS NOT NULL
  
AND (total_worker_time/execution_count) > 100
--ORDER BY avg_cpu_cost DESC;
--ORDER BY execution_count DESC;
ORDER BY total_worker_time DESC;


 
Disk IO Query

SELECT TOP 20
    total_logical_reads
/execution_count AS avg_logical_reads,
    total_logical_writes
/execution_count AS avg_logical_writes,
    total_worker_time
/execution_count AS avg_cpu_cost, execution_count,
    total_worker_time
, total_logical_reads, total_logical_writes,
    
(SELECT DB_NAME(dbid) + ISNULL('..' + OBJECT_NAME(objectid), '')
        
FROM sys.dm_exec_sql_text([sql_handle])) AS query_database,
    
(SELECT SUBSTRING(est.[text], statement_start_offset/2 + 1,
        
(CASE WHEN statement_end_offset = -1
            
THEN LEN(CONVERT(nvarchar(max), est.[text])) * 2
            
ELSE statement_end_offset
            
END - statement_start_offset
        
) / 2)
        
FROM sys.dm_exec_sql_text(sql_handle) AS est) AS query_text,
    last_logical_reads
, min_logical_reads, max_logical_reads,
    last_logical_writes
, min_logical_writes, max_logical_writes,
    total_physical_reads
, last_physical_reads, min_physical_reads, max_physical_reads,
    
(total_logical_reads + (total_logical_writes * 5))/execution_count AS io_weighting,
    plan_generation_num
, qp.query_plan
FROM sys.dm_exec_query_stats
    
OUTER APPLY sys.dm_exec_query_plan([plan_handle]) AS qp
WHERE [dbid] >= 5 AND DB_NAME(dbid) IS NOT NULL
  
and (total_worker_time/execution_count) > 100
ORDER BY io_weighting DESC;
--ORDER BY avg_logical_reads DESC;
--ORDER BY avg_logical_writes DESC;
--ORDER BY avg_cpu_cost DESC;

1 comment:

jasmine said...

My cousin recommended this blog and she was totally right keep up the fantastic work!








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