Re: banging my head against SelectQueryTst

From: Dirk Olmes (dirk.olme..mx.de)
Date: Tue Feb 18 2003 - 14:40:54 EST

  • Next message: Holger Hoffstätte: "Modeler look&feel"

    >> Can someone please explain the design goal behind the whole trimming
    >> of CHAR columns, please? I remember that in the past CHAR columns
    >> were handled more efficiently by DBMSs than VARCHAR but I remember
    >> having read in the Oracle docs that this is no longer true.
    >
    > That's what I heard in the past too. Not sure what is the current
    > situation. In any event I suspect it to be database-dependent.

    Right. MySQL does not pad CHAR columns, Holger reported this some time
    ago IIRC.

    > Also since there is a CHAR type in JDBC, we must support it correctly.
    > It is up to the users to avoid using it in the design.

    Ok. When I initially found out about the behaviour of
    QualifierTranslator, I wasn't too exited about the behaviour. Now, that
    I have thought a bit more about it, I like it better and better. One
    thing I'd like to experiment with a bit more is the performance of
    RTRIM() queries against normal queries.

    > I guess for now we may need a PostgresQualifierTranslator, just like
    > Oracle's. Later we may refactor it into an adapter-independent
    > subclass of QualifierTranslator.

    Just for testing I added an OracleQualifierTranslator (since Postgres
    has RTRIM, too) to the PostgresAdaptor and re-ran the SelectQueryTst.
    It's all green now :-) So I guess refactoring OracleQualifierTranslator
    to a CharColumnTrimQualifierTranslator would be the next logical step.

    -dirk



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