How to reject parallelism in a query ?

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How to reject parallelism in a query ?

SQL Guy 1

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February 12, 2014 at 12:14 pm

#304319

While tuning a S.P. for performance, I found that it better executes without parallelism. But I don't want to change it's threshold in production, what I am looking for is some hint or any other method that works on a query level.

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Luis Cazares SSC Guru Points: 183706 More actions · Answer 1

You could use the query hint MAXDOP.

Check the reference: http://technet.microsoft.com/en-us/library/ms181714.aspx

Example F.

Luis C.
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Grant Fritchey SSC Guru Points: 399278 More actions · Answer 2

Also, check the cost threshold for parallelism on the server. The default value is 5 and that is radically low for most systems. Changing that to an appropriate value (say 50) will eliminate a lot of unnecessary parallelism.

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Jeff Moden SSC Guru Points: 1004638 More actions · Answer 3

I was going to suggest disabling bit 29 on DBCC TIMEWARP which suppresses the availability of parallel universes.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

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