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FireHost Cursor in SQL Server 2000

  • August 7, 2005 at 11:52 pm

    #67033

    Hi All,

    I need to know the answers for the below mentioned questions:

    1) Is there anything called FireHost Cursor in SQL Server 2000? If so what is it ?

    2) If we have indexes on all the columns of a table, it is called Covered Index. By having Covered Index on a table, will it reduce the performance while querying that table ?

    Can any one please help me ?

    Thanks in advance,

    Subhash

  • August 8, 2005 at 12:08 am

    #580328

    1. There's a "firehose cursor" in SQL 2000.  It's a phenomenon arising from the interaction of SQL2000 and clients (generally Enterprise Manager).  It's something I've come across only a couple of times when using EM.  There's a discussion at http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q237398&

    2. A covered index can improve performance in many cases, provided your main access and data requirements are known in advance and then the index is constructed accordingly.  Don't just chuck all the columns into the index without forethought.  And, don't waste time and resources making your clustered index a covered index.

     


    Cheers,
    - Mark

  • August 8, 2005 at 12:10 am

    #580329

    Thanks Mark.

  • August 9, 2005 at 9:15 am

    #580768

    A covered index isn't necessarily every column in a table, but is an index that covers all the columns used in a particular query.  For instance, if you have a table with a bunch of columns, including A, B and C, which are indexed, a query such as SELECT A, B, C FROM sampletable WHERE A=1 AND B=2 AND C=3 would use the indexes rather than having to get data from the table data pages.

    So long, and thanks for all the fish,

    Russell Shilling, MCDBA, MCSA 2K3, MCSE 2K3

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