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  1. #1
    Join Date
    Mar 2003

    Question Unanswered: Table reorg issue - Query Plan

    Our Informix (7.3.1) DBA reorgs the tables by dropping them and then reloading them with data, then recreate objects (indexes,etc). Finally, update statistics is run at midnight for cleanup. These reorgs are being run to eliminate the in place alters for an upcoming IFX 9.3 upgrade project.
    The issue we are seeing is that Informix seems to choose another query plan then the one that was originally used before the 'reorg' and it is often slower. One statement that had a cost of 186 before now has a cost of 1570. Can anyone elaborate on this problem and suggest alternatives? Thanks.
    Last edited by cghami; 03-20-03 at 11:55.

  2. #2
    Join Date
    Aug 2002
    First of all, you don't need to eliminate existing
    in-place-alters before upgrading to 9.3.
    It should not be a problem to take these outstanding
    in-place-alters over to 9.30.

    The only pitfall is that if you decide to go back from
    9.30 to 7.31 (onmode -b 7.3) after the migration, you have to
    eliminate all outstanding in-place-alters.
    So this might be the only reason to eliminate these
    outstanding in-place-alters before the migration to 9.30.

    Unload/Re-Create/Load is not necessary.
    A dummy-update statement on all rows of a table
    is enough.

    Download the 'tx_split' utility from my website. This utility
    is able to split big transactions into smaller transaction
    groups, so you will be able to run these dummy-updates
    on a production server without the risk of long transactions.

    Best regards

    IT-Consulting Herber

    Download the IFMX Database-Monitor for free at:

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