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DROPCLEANBUFFERS scope?

  • April 13, 2011 at 8:09 am

    #235655

    When I run CHECKPOINT along with DBCC DROPCLEANBUFFERS, what is the scope? Is it clearing the buffer for the database I specified or for the whole SQL instance?

    Thanks,

    -Tim

  • April 13, 2011 at 9:11 am

    #1311079

    It's going after the instance. Why would you do that?

    I mean, for testing purposes, fine, but I wouldn't suggest running that in production.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
    - Theodore Roosevelt

    Author of:
    SQL Server Execution Plans
    SQL Server Query Performance Tuning

  • April 13, 2011 at 9:43 am

    #1311112

    The checkpoint is database-specific, the drop clean buffers drops every single clean page from the entire data cache.

    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
    We stand on the bridge and no one may pass

  • April 13, 2011 at 9:46 am

    #1311120

    Grant -

    Thanks for the info and yes I am testing the performance of a query. I was hoping to be able to test a separate DB on the same istance without effecting the production DB. Oh well. Off to the test environment.

    Thanks again,

    -Tim

  • April 13, 2011 at 9:50 am

    #1311128

    Never test on the production server. Ever.

    That's what dev/test environments are for.

    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
    We stand on the bridge and no one may pass

  • April 13, 2011 at 9:54 am

    #1311134

    @gilamonster -

    Thanks for both posts.

    All the best,

    -Tim

  • April 13, 2011 at 10:06 am

    #1311151

    Timothy Straub (4/13/2011)

    Grant -

    Thanks for the info and yes I am testing the performance of a query. I was hoping to be able to test a separate DB on the same istance without effecting the production DB. Oh well. Off to the test environment.

    Thanks again,

    -Tim

    Heck yes, off to the test environment.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
    - Theodore Roosevelt

    Author of:
    SQL Server Execution Plans
    SQL Server Query Performance Tuning

  • April 13, 2011 at 1:06 pm

    #1311268

    Grant Fritchey (4/13/2011)

    , off to the test environment.

    *Totally irrelevant thought*

    .. to the TestMobile Batman!

    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
    We stand on the bridge and no one may pass

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