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MaxDB 7.7 bad join performance

Hello,

after upgrading from MaxDB 7.6 to MaxDB 7.7 we got performance problems executing a sql query. It is a join over 3 tables, nothing special, 7.6 ran the query in less a second, 7.7 needs about 1 minute 50 sec. to comlpete. Running explain against both versions gives the same strategy, I also did a statistics update after the db upgrade. Are there new parameters in 7.7 relating to joins?

Thanks an best regards

Tiberius

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  • Posted on Oct 02, 2009 at 10:00 AM

    Hi there,

    that description is a nice story but does not allow anybody to analyze anything.

    We don't know the query or the execution plans or the execution times or the database setups.

    We don't know anything yet to help you with your request.

    If you're a SAP customer, facilitate support for this, as the forum software is too restrictive to do any real analysis.

    If you're a NON-SAP MaxDB User, please start with checking the database parameters.

    As you wrote the execution strategy is the same, then something else seems to be much slower now (e.g. I/O).

    regards,

    Lars

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    • Ok, now this really got my interest!

      Can you provide a backup file of your database so that we can reproduce the behavior?

      Or can you give us the complete commands to build-up the tables/indexes/data with which you can reproduce the problem?

      Based on your description I made some tests, but I wasn't able to make this problem occur.

      regards,

      Lars

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