query optimizer

  • Hi,

    how can we know that particular query is taking long time and we have to optimize that,and i heared that query optimization through sqlserver profiler degrades the perfomance.?

    what is diff between clustered index seek and bookmark look?

  • shahbaz.oradba (7/14/2008)


    Hi,

    how can we know that particular query is taking long time and we have to optimize that,and i heared that query optimization through sqlserver profiler degrades the perfomance.?

    Sorry, I don't understand your question.

    what is diff between clustered index seek and bookmark look?

    http://sqlinthewild.co.za/index.php/2007/11/15/execution-plan-operations-scans-and-seeks/

    The bookmark lookup was renamed to key lookup in SQL 2005.

    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
  • GilaMonster (7/15/2008)


    shahbaz.oradba (7/14/2008)


    Hi,

    how can we know that particular query is taking long time and we have to optimize that,and i heared that query optimization through sqlserver profiler degrades the perfomance.?

    If you are going to use the SQL Profiler, it does put some overhead onto the server, but again, it will depend on what you are actually looking for,as well as how many results you want in the profiler. Filter as much as you can in profiler will also decrease its overhead.

    there are a number of other ways to check once you have the query that is running a long time.

    what is diff between clustered index seek and bookmark look?

    http://sqlinthewild.co.za/index.php/2007/11/15/execution-plan-operations-scans-and-seeks/

    The bookmark lookup was renamed to key lookup in SQL 2005.

    To answer this question,

    Index Seek, is a good thing, means that it is using the clustered index and it is seeking only the rows it needs. If you read the previous post, it explains it very nicely.

  • Finding stored procedures and the time required for same

    You may want to refer to sys.dm views and functions for example

    Select * sys.dm_exec_query_stats to find those taking the longest to perform. This reports among other items the Total elapsed time, in microseconds, for completed executions of the query plan.

    For an explanation of the data returned refer to BOL

    ms-help://MS.SQLCC.v9/MS.SQLSVR.v9.en/tsqlref9/html/eb7b58b8-3508-4114-97c2-d877bcb12964.htm

    Querying this and other sys.dm views and functions might yield you the data you need in the shortest period of time and with the least additional work load on the server.

    If everything seems to be going well, you have obviously overlooked something.

    Ron

    Please help us, help you -before posting a question please read[/url]
    Before posting a performance problem please read[/url]

  • Just bear in mind that the entriesd in the query stats dmv are transient and are removed when the plan is discarded from cache.

    It cannot be guaranteed that everything that has run on the server is in the plan 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
  • shahbaz.oradba (7/14/2008)


    Hi,

    how can we know that particular query is taking long time and we have to optimize that,and i heared that query optimization through sqlserver profiler degrades the perfomance.?

    what is diff between clustered index seek and bookmark look?

    Profiler is a GUI for server side traces. You can setup a server side trace that logs long running queries which will have minimal impact on performance. See BOL for how to.

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