Re: Caching of Queries - Mailing list pgsql-performance

From Tom Lane
Subject Re: Caching of Queries
Date
Msg-id 18766.1096262336@sss.pgh.pa.us
Whole thread Raw
In response to Re: Caching of Queries  (Neil Conway <neilc@samurai.com>)
Responses Re: Caching of Queries  (Mitch Pirtle <mitch.pirtle@gmail.com>)
Re: Caching of Queries  ("Matthew Nuzum" <cobalt@bearfruit.org>)
List pgsql-performance
Neil Conway <neilc@samurai.com> writes:
> I think the conclusion of past discussions about this feature is that
> it's a bad idea. Last I checked, MySQL has to clear the *entire* query
> cache when a single DML statement modifying the table in question is
> issued.

Do they actually make a rigorous guarantee that the cached result is
still accurate when/if it is returned to the client?  (That's an honest
question --- I don't know how MySQL implements this.)

IIRC, in our past threads on this topic, it was suggested that if you
can tolerate not-necessarily-up-to-date results, you should be doing
this sort of caching on the client side and not in the DB server at all.
I wouldn't try that in a true "client" scenario, but when the DB client
is application-server middleware, it would make some sense to cache in
the application server.

            regards, tom lane

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