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Identifying Queries Running Slower Than Normal Expand / Collapse
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Posted Thursday, August 7, 2008 10:08 AM
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It would be nice if the Main Article has a line or Item which says" This Application is not for SQL 2000"
Post #548441
Posted Thursday, August 7, 2008 10:42 AM
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I've been playing around with it this morning and have already found it helpful. We run massive matching (fuzzy) and deduping jobs that can run for days so tuning for ET is high on our list.

Thanks.

Steve
Post #548473
Posted Thursday, August 7, 2008 12:53 PM
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Hey all..

Does this work on SqlExpress 2005 ?

if so, i got the error
Msg 102, Level 15, State 1, Procedure dba_QueryTimeDelta, Line 49
Sintaxe incorreta próxima a '.'.

(incorrect sintax near to '.'.)

the line is CROSS APPLY sys.dm_exec_sql_text(qs.plan_handle) qt

looks like sys.dm_exec_sql_text cant be executed or something like that,
it is on my master, functions and all..
but still can't run it.

thx.
Post #548595
Posted Thursday, August 7, 2008 1:16 PM
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-- reformat original code from author's Word document.
-- Hope this help.


CREATE PROC [dbo].[dba_QueryTimeDelta]
AS
/*----------------------------------------------------------------------

Purpose: Identify queries that are running slower than normal
, when taking into account IO volumes.
------------------------------------------------------------------------

Parameters: None.

Revision History:
13/01/2008 Ian_Stirk@yahoo.com Initial version

Example Usage:
1. exec YourServerName.master.dbo.dba_QueryTimeDelta

----------------------------------------------------------------------*/

BEGIN

-- Do not lock anything, and do not get held up by any locks.
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
-- Identify queries running slower than normal.
SELECT TOP 100
[Runs] = qs.execution_count
--, [Total time] = qs.total_worker_time - qs.last_worker_time
, [Avg time] = (qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1)
, [Last time] = qs.last_worker_time
, [Time Deviation] = (qs.last_worker_time - ((qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1)))
, [% Time Deviation] = CASE WHEN qs.last_worker_time = 0 THEN 100
ELSE (qs.last_worker_time - ((qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1))) * 100
END / (((qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1)))
, [Last IO] = last_logical_reads + last_logical_writes + last_physical_reads
, [Avg IO] = ((total_logical_reads + total_logical_writes + total_physical_reads)
- (last_logical_reads + last_logical_writes + last_physical_reads))
/ (qs.execution_count - 1)
, [Individual Query] = SUBSTRING (qt.text,qs.statement_start_offset/2,
(CASE WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2
ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)
, [Parent Query] = qt.text
, [DatabaseName] = DB_NAME(qt.dbid)
INTO #SlowQueries
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.plan_handle) qt
WHERE qs.execution_count > 1
ORDER BY [% Time Deviation] DESC

-- Calculate the [IO Deviation] and [% IO Deviation].
-- Negative values means we did less I/O than average.
SELECT TOP 100 [Runs]
, [Avg time]
, [Last time]
, [Time Deviation]
, [% Time Deviation]
, [Last IO]
, [Avg IO]
, [IO Deviation] = [Last IO] - [Avg IO]
, [% IO Deviation] =
CASE WHEN [Avg IO] = 0
THEN 0
ELSE ([Last IO]- [Avg IO]) * 100 / [Avg IO]
END
, [Individual Query]
, [Parent Query]
, [DatabaseName]
INTO #SlowQueriesByIO
FROM #SlowQueries
ORDER BY [% Time Deviation] DESC

-- Extract items where [% Time deviation] less [% IO deviation] is 'large'
-- These queries are slow running, even when we take into account IO deviation.
SELECT TOP 100 [Runs]
, [Avg time]
, [Last time]
, [Time Deviation]
, [% Time Deviation]
, [Last IO]
, [Avg IO]
, [IO Deviation]
, [% IO Deviation]
, [Impedance] = [% Time Deviation] - [% IO Deviation]
, [Individual Query]
, [Parent Query]
, [DatabaseName]
FROM #SlowQueriesByIO
WHERE [% Time Deviation] - [% IO Deviation] > 20
ORDER BY [Impedance] DESC

-- Tidy up.
DROP TABLE #SlowQueries
DROP TABLE #SlowQueriesByIO
END



Post #548610
Posted Thursday, August 7, 2008 2:22 PM


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My apologies for the formatting. I'm not sure what the text editor did to the article, but it has been reformatted to fit on the screen.








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Forum Etiquette: How to post data/code on a forum to get the best help
Post #548660
Posted Thursday, August 7, 2008 11:31 PM
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Thanks for the modification. It was a good article.:)


Post #548860
Posted Thursday, August 7, 2008 11:53 PM


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Very Helpful Article.
Will work on it in detail in near future to use it according to my own requirements...

Atif Sheikh


----------------------------------------------------------------------------------------------------------------------------------------------------------------------

Sometimes, winning is not an issue but trying.

You can check my BLOG here

Post #548865
Posted Friday, August 8, 2008 10:19 AM
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This looks like it could be really interesting, but there's bugs in the code. Lots of spaces are missing and cause syntax errors. Also, it needs to be coded to be aware of divide by zero errors.

I look forward to seeing an updated version of this.
Post #549393
Posted Saturday, August 9, 2008 1:33 AM


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No error found to me. I copied the code from the attached doc file and it executed well...

Atif Sheikh


----------------------------------------------------------------------------------------------------------------------------------------------------------------------

Sometimes, winning is not an issue but trying.

You can check my BLOG here

Post #549709
Posted Saturday, August 9, 2008 7:52 AM


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I've added a NullIf function to prevent the divide by zero error:


------------------------------------------------------------------------
-- Purpose: Identify queries that are running slower than normal,
-- when taking into account IO volumes.
--------------------------------------------------------------------------
ALTER PROC [dbo].[dba_QueryTimeDelta]
AS
BEGIN
-- Do not lock anything, and do not get held up by any locks.
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

-- Identify queries running slower than normal.
SELECT TOP(100)
[Runs] = qs.execution_count,
-- [Total time] = qs.total_worker_time - qs.last_worker_time,
[Avg time] = (qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1),
[Last time] = qs.last_worker_time,
[Time Deviation] = (qs.last_worker_time - ((qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1))),
[% Time Deviation] = CASE WHEN qs.last_worker_time = 0 THEN 100
ELSE (qs.last_worker_time - ((qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1))) * 100
END / NullIf((((qs.total_worker_time - qs.last_worker_time) / (qs.execution_count - 1))), 0),
[Last IO] = last_logical_reads + last_logical_writes + last_physical_reads,
[Avg IO] = ((total_logical_reads + total_logical_writes + total_physical_reads) - (last_logical_reads + last_logical_writes + last_physical_reads)) / (qs.execution_count - 1),
[Individual Query] = Substring (qt.text,qs.statement_start_offset / 2,
(CASE WHEN qs.statement_end_offset = -1
THEN Len(Convert(nvarchar(Max), qt.text)) * 2
ELSE qs.statement_end_offset
END - qs.statement_start_offset)/2),
[Parent Query] = qt.text,
[DatabaseName] = DB_NAME(qt.dbid)
INTO #SlowQueries
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.plan_handle) qt
WHERE qs.execution_count > 1
ORDER BY [% Time Deviation] DESC

-- Calculate the [IO Deviation] and [% IO Deviation].
-- Negative values means we did less I/O than average.
SELECT TOP 100 [Runs],
[Avg time],
[Last time],
[Time Deviation],
[% Time Deviation],
[Last IO],
[Avg IO],
[IO Deviation] = [Last IO] - [Avg IO],
[% IO Deviation] = CASE WHEN [Avg IO] = 0 THEN 0
ELSE ([Last IO]- [Avg IO]) * 100 / [Avg IO]
END,
[Individual Query],
[Parent Query],
[DatabaseName]
INTO #SlowQueriesByIO
FROM #SlowQueries
ORDER BY [% Time Deviation] DESC

-- Extract items where [% Time deviation] less [% IO deviation] is 'large'
-- These queries are slow running, even when we take into account IO deviation.
SELECT TOP(100)
[Runs],
[Avg time],
[Last time],
[Time Deviation],
[% Time Deviation],
[Last IO],
[Avg IO],
[IO Deviation],
[% IO Deviation],
[Impedance] = [% Time Deviation] - [% IO Deviation],
[Individual Query],
[Parent Query],
[DatabaseName]
FROM #SlowQueriesByIO
WHERE [% Time Deviation] - [% IO Deviation] > 20
ORDER BY [Impedance] DESC

-- Tidy up.
DROP TABLE #SlowQueries
DROP TABLE #SlowQueriesByIO

END
GO
Post #549771
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