Re: Big selects on PostGres : Configuring Statement.setFetchSize() of a selectquery

From: Andrey Razumovsky (razumovsky.andre..mail.com)
Date: Sun May 24 2009 - 05:52:21 EDT

  • Next message: Andrus Adamchik: "Re: [VOTE] Cayenne 3.0M6"

    I should say my tests on Postgres and mysql didn't show any results. If I
    use small heap size, i get OutOfMemory no matter which fetch size was set.
    Fetch speed and memory usage are the same. Seems drivers just ignore this
    parameter. Stephane, did your workaround help you?

    Drivers of hsql, postres, mysql didn't throw any exceptions.. Maybe other
    DBMS drivers work well with this param. I'm going to commit today or
    tomorrow. Nothing will break anything if we add this ability.

    Andrey

    2009/5/21 Andrus Adamchik <andru..bjectstyle.org>

    > Cool :-)
    >
    > On May 21, 2009, at 3:59 PM, Andrey Razumovsky wrote:
    >
    > Now when I know of this JDBC feature, I'd prefer to have it in Cayenne
    >> sooner that later. We would also want to have it for other queries than
    >> just
    >> only SelectQuery.
    >>
    >
    > Absolutely. This has to be a part of the QueryMetadata on the backend. On
    > the frontend any query that can potentially select data should have a
    > corresponding setter.
    >
    > Could someone help me testing it against different types
    >> of database if I commit?
    >>
    >
    > I can test it on almost all DB's that we support. Of course we should have
    > Cayenne unit tests that will provide regression (i.e. driver XYZ doesn't
    > throw UnsupportedOperationException when we call a corresponding JDBC
    > method).
    >
    > In addition to that I'd like to see if there's really memory/speed savings
    > when using that (i.e. is it really worth it). For that I suggest writing a
    > JDBC test outside of Cayenne, that can be run in profiler against different
    > DB's.
    >
    > Andrus
    >



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