Tuesday, February 14, 2012

Do you disable parallelism on OLTP SQL Servers ?

We have seen a few problems when we notice high CPU all of a sudden and
realize that parallelism is the culprit on our SQL 2K SQL Servers. We have
tried to use the maxdop hint to disable parallelism for the respective
queries we bumped into but time and again , we contemplate on whether we
need to disable parallelism on the server itself. Can someone comment ?
ThanksHi Hassan
Although it's theoretically possible that parallelism might be better on
than off in some OLTP scenarios, I've never seen this to be true.
I nearly always recommend turning parallelism off on OLTPs - it's generally
better to use multi-CPUs for processing multiple queries concurrently in
OLTP workload than to allow single queries to utilise multiple-CPUs.
Regards,
Greg Linwood
SQL Server MVP
http://blogs.sqlserver.org.au/blogs/greg_linwood
"Hassan" <hassan@.hotmail.com> wrote in message
news:eg46nl9eHHA.3932@.TK2MSFTNGP02.phx.gbl...
> We have seen a few problems when we notice high CPU all of a sudden and
> realize that parallelism is the culprit on our SQL 2K SQL Servers. We have
> tried to use the maxdop hint to disable parallelism for the respective
> queries we bumped into but time and again , we contemplate on whether we
> need to disable parallelism on the server itself. Can someone comment ?
> Thanks
>

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