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Subquery Running Slow

  • July 14, 2011 at 7:51 am

    #244302

    Hi Guys,

    I need a suggestion as to what is going on with my query... I have a query with correlated subqueries in it... it is running too slow now and takes almost 2 minutes to get the result while the same query used to take around 10 seconds to get the result week back. Nothing has been changed in our environment and even the data is still the same... What might be the issue??? I did change the correlated queries now and it running fast; however, I was thinking why there is change while running old query now and a week back?

    Thanks!

  • July 14, 2011 at 8:32 am

    #1352856

    Almost impossible to answer based on the information provided so far.

    Parameter sniffing? Out of date statistics? Missing/dropped indexes? Changed data volume? Heavy server load? Disc issues? ...

    Please remember: neither do we see what you see nor can we look over your shoulder.

    So please provide the query, table def and index definition of the related source tables as well as the actual execution plan (preferrably both: one for the "slow" query and one for the "fast" one).


    Lutz
    A pessimist is an optimist with experience.

    How to get fast answers to your question[/url]
    How to post performance related questions[/url]
    Links for Tally Table [/url] , Cross Tabs [/url] and Dynamic Cross Tabs [/url], Delimited Split Function[/url]

  • July 14, 2011 at 8:43 am

    #1352864

    Thanks LutzM for your response. I was just looking for things I should look for in such cases when nothing has changed in the environment or data/indexes/query/parameters.

  • July 14, 2011 at 9:46 am

    #1352916

    Start with comparing the actual execution plans if both are exactly the same.


    Lutz
    A pessimist is an optimist with experience.

    How to get fast answers to your question[/url]
    How to post performance related questions[/url]
    Links for Tally Table [/url] , Cross Tabs [/url] and Dynamic Cross Tabs [/url], Delimited Split Function[/url]

  • July 14, 2011 at 11:48 am

    #1353009

    Yes. Thanks you.

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