Re: 'prepare' is not quite schema-safe

From: Vlad <marchenko(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general(at)postgresql(dot)org, dbdpg-general(at)gborg(dot)postgresql(dot)org
Subject: Re: 'prepare' is not quite schema-safe
Date: 2005-05-02 05:05:45
Message-ID: cd70c681050501220564cf735a@mail.gmail.com
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btw, after re-reading the second part of your comment once again, I
have a (clarification) question:

so is it possible that a successfully prepared (and possibly a couple
of times already executed) query will be invalidated by postgresql
for some reason (like lack of memory for processing/caching other
queries)? Assuming that no database structure changes has been
performed.

If the answer is YES, then it's important to double check that the
dbd::pg driver would try to handle such situation appropriate - like
re-prepare query with postgresql.

> Hmm. The above is arguably a DBD::Pg bug: it should not expect that
> it's okay to use the same prepared statement in both cases. I do not
> know what the spec is for "prepare_cached", but it sure seems that the
> concept is fraught with danger --- the client-side driver has very
> little hope of knowing what server-side events might be reasons to
> invalidate the query cache. (Not that the server side is presently
> all that good about it, but at least the server side is fixable
> in principle ;-))
>
> regards, tom lane
>

--

Vlad

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