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  1. #1
    Join Date
    Aug 2011
    Posts
    2

    Unanswered: Index size estimation

    Hi,

    Can someone please help me out to calculate the index size. I checked using dbschema -d dbname -t tblname. I could see the index size value. Is this right method to determine the index size or is there any other menthod to estimate the index size

    Thanks

  2. #2
    Join Date
    Dec 2003
    Location
    North America
    Posts
    146
    you can try using oncheck -pt <db_name>:<db_owner>.<table_name> <cr> from the command line and you'll see a section of values for each index after the data section of the output. Though you can specify an First extent size and next extent size when creating a table, I don't know how the First extent size and next extent size values are derived for indexes.

    AIX_production > oncheck -pt FIN8.4_Live:sysadm.ps_employee <cr>

    In the section for each index you'll see values called "Number of Pages Allocated" and "Number of Pages Used", so use whichever value is more meaningful to you and multiply by the page size (AIX has 4k pages) and you'll have a pretty good idea how much space each index is using.

  3. #3
    Join Date
    Aug 2011
    Posts
    2

    Re:

    Thanks a lot for your reply . I have a clarification here . No of data pages mentioned in the oncheck command doesnt match with the index size fetched using dbschema command. What is the significance of index size value which is reported using dbschema calculated.

  4. #4
    Join Date
    Dec 2003
    Location
    North America
    Posts
    146
    Sorry to say I have no idea what "index size" refers to in the output returned from running dbschema on a table, I've never paid any attention to it because I've always used oncheck.

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