August 13, 2014 at 6:22 am
Hi all
A bit of a strange one in my eyes, is it possible to experience CXPACKETS when MAXDOP is set to 1? Was doing some testing on an AX box yesterday, MAXDOP set to 1 and when looking at wait statistics noticed (albeit a small amount) of CXPACKET waits.
Thanks as always
D
'Only he who wanders finds new paths'
August 13, 2014 at 6:36 am
Server maxdop can be overridden.
If your instance is MAXDOP 1 and I run a query with OPTION(maxdop 8), my query can parallel up to 8 threads. That's probably what's happening.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
August 13, 2014 at 7:04 am
Sorry Gail, should have added that I've gone through the sprocs and had a look, no overrides via a hint that I can see.
D
'Only he who wanders finds new paths'
August 13, 2014 at 7:12 am
Ah-hoc query, SQL from an app.
If nothing at all is running in parallel, there should be no cxpacket (though maybe some system stuff can ignore the maxdop setting, not sure)
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
August 13, 2014 at 7:45 am
Thanks Gail
Well, I cant be 100% sure that an ad hoc query was not ran during testing but I'd like to think that isn't the case. I did wonder if it was some internal process but really not sure!!!
D
'Only he who wanders finds new paths'
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