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Wait stats OLEDB and others Expand / Collapse
Posted Monday, June 13, 2011 5:15 AM
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I have a server which is hardly used most of the time but for a few hours a night there is huge activity with 5 or so minutes on the hour for those periods where activity is huge and SQL querys take an extensive amount of time to compile.
From my understanding conclusions cannot be drawn from SQLTRACE_BUFFER_FLUSH and LAZYWRITER_SLEEP ?
As for SOS_SCHEDULER_YIELD the processor % is below 50 across all CPU and the processor queue length stays below 1 for these peak periods. So there doesn’t seem to be a CPU problem.
Memory stays good available memory is stable at 4 GB’s buffer cache 100% recompiles 0

1) So what conclusions can be drawn from my wait stats?
2) What does the high MAX_wait for the OLEDB mean?

Many thanks
Waiting_task wait_time_ms Max_wait Signal
SQLTRACE_BUFFER_FLUSH 147559 590310984 19562 71031
LAZYWRITER_SLEEP 605298 590285906 16328 306625
SOS_SCHEDULER_YIELD 20545861 189581015 16125 189577359
PAGEIOLATCH_SH 7824061 164688250 16406 1754515
OLEDB 36674 90676890 15627453 0
PAGEIOLATCH_EX 3679075 71624656 16328 405343
WRITELOG 5075655 24172640 5171 5092062
PAGELATCH_EX 12399831 21708484 4250 17953000
Post #1124164
Posted Monday, June 13, 2011 5:35 AM



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The lazywriter is supposed to sleep a lot. That's why it's called lazy. There are a fair few wait types that should just be ignored.

As for the OLEDB wait, I'd conclude you're using linked servers a lot.

Is there a particular problem that you're investigating here?

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

We walk in the dark places no others will enter
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Post #1124176
Posted Monday, June 13, 2011 6:37 AM
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Hi , This is a virtual server not sure what difference that will make?

But in answer to your questions there are no linked servers, so how else would I get OLEDB waits?

The problem is that during these high usage peeks some queries take a very long time which cause the application which is querying the DB to time out ( As I don’t have any high lock waits I presume there must be a bottle neck) , I will run perfmon counters to see what is happing with the disk ,cpu and memory.

But I am trying to get more familiar with wait stats to see if I can draw any conclusions from it I see no lock’s CPU or memory pressure. So I just want to see how much I can gain from the wait stats and to figure out why I have OLEDB waits (server was restarted a few days ago)

Many thanks
Post #1124208
Posted Friday, July 26, 2013 2:46 AM


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Looks like we're in the same boat.
I'm also looking into reducing OLEDB waits.

Here are some links I've found that might help you out.

I'm pretty sure my OLEDB waits are caused by views using linked servers or other DBs. Looking into ways to better this but can't find any decent info on Views with linked servers and / or other DBs and the alternatives.
Replication might be my only option.

Hope the links help you out.

For better, quicker answers on T-SQL questions, read Jeff Moden's suggestions.

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