| From: | Andrew Sullivan <andrew(at)libertyrms(dot)info> |
|---|---|
| To: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: IN vs EXIIST |
| Date: | 2002-09-19 12:40:37 |
| Message-ID: | 20020919084037.C326@mail.libertyrms.com |
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| Lists: | pgsql-general |
On Thu, Sep 19, 2002 at 06:36:56PM +0900, Jean-Christian Imbeault wrote:
>
> Maybe EXISTS is not always faster than IN ?
I haven't been reading this thread very carefully, but that one is
_certainly_ true. In testing, we have had a wide variety of results
with IN versus EXISTS. It seems to have to do with the relative size
of the two sides. I haven't come up with a perfect rule for deciding
yet.
NOT IN/NOT EXISTS is more often a clear-cut case: NOT EXISTS is
_almost_ (but only almost) always faster.
A
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Andrew Sullivan 204-4141 Yonge Street
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