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  1. #1
    Join Date
    Jun 2011

    Unanswered: Slow Union SQL 2008 R2

    I have upgraded to SQL 2008 R2 and windows 2008 R2 (64Bit) from SQL 2005 and Windows 2003(32bit), both on VMware.

    I have long query which uses UNION. The query runs on SQL 2005(3 minutes) and SQL 2008 R2 (over 12 hours).

    I have enabled the Lock Pages in Memory Option, no different. The query Plan is same on both servers.

    Any ideas?

  2. #2
    Join Date
    Mar 2007
    Holmestrand, Norway
    Are you looking at actual or estimated execution plans? Actual execution plan may in some cases be very different from the estimated.

    What is the "page life expectancy" and "buffer cache hit ratio" performance counters showing during execution?

    How is the memory pressure on the physical host? I know that VMware allow for over commit of memory, but I do not know whether VMware will swap memory to disk. If VMware does so, it could possibly cause cache to be swapped, even if lock pages in memory is set.
    Ole Kristian Velstadbråten Bangås - Virinco - - Facebook - Twitter

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