From: | Thomas Schoen <t(dot)schoen(at)vitrado(dot)de> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: ORDER BY with plpgsql parameter |
Date: | 2004-06-02 16:12:38 |
Message-ID: | 200406021812.38704.t.schoen@vitrado.de |
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Thread: | |
Lists: | pgsql-general |
> You want to build a dynamic query (sorted in different ways depending on
> a function parameter).
yes.
>
> You don't want to use the dynamic query statement (EXECUTE).
yes, because it seems to me, that "for in execute" is slower than the direct
way. Is that right?
>
> The whole point of plpgsql is that the queries can be compiled and
> pre-planned. If you want to change the sorting then that implies a
> different plan, which implies using the dynamic query feature.
OK, does that mean, that it is no difference in performance whether i use "FOR
IN EXECUTE" or two different functions with different sorting?
>
> What you want to do is possible if you use one of the interpreted
> languages, e.g. pltcl/plperl (plphp?). Of course, that means none of
> your query plans get compiled.
What happens to the query plan if i use function-parameters in the where
clause of my statement? Is the function recompiled then?
Conclusion: if i want to sort inside the functions depending on function
parameters, the best way to do it is using "FOR IN EXECUTE"??
Is that right?
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