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Re: [JDBC] Support for JDBC setQueryTimeout, et al.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Stephen Frost <sfrost(at)snowman(dot)net>
Cc: Radosław Smogura <rsmogura(at)softperience(dot)eu>, Magnus Hagander <magnus(at)hagander(dot)net>, David Fetter <david(at)fetter(dot)org>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>, PostgreSQL JDBC List <pgsql-jdbc(at)postgresql(dot)org>, robertmhaas(at)gmail(dot)com
Subject: Re: [JDBC] Support for JDBC setQueryTimeout, et al.
Date: 2010-10-15 14:38:54
Message-ID: 20260.1287153534@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-jdbc
Stephen Frost <sfrost(at)snowman(dot)net> writes:
> * Radosaw Smogura (rsmogura(at)softperience(dot)eu) wrote:
>> But benefits of pooling statements are much more greater then RESET ALL,
>> because you can take advance of precompiling prepared statements,
>> increasing performance; it is comparable to using connection pool instead
>> of starting physical connections.

> errr, I don't believe RESET ALL touches cache'd plans and whatnot (which
> is actually a problem I've run into in the past, because changing the
> search_path also doesn't invalidate plans, and neither does set role, so
> you end up with cache'd plans that try to hit things you don't have
> permissions to any more :( ).

Yeah, actually what you need is DISCARD ALL when reassigning a
connection to another client.  Anything less than that assumes the
clients are cooperating closely, ie they *want* the same prepared
statements etc.  But even if you make that assumption, a pooler that
isn't even capable of sending an ABORT between clients doesn't seem
usable to me.  For example, if a client loses its network connection
mid-transaction, that failure will cascade to other clients if you
don't have any ability to reset the database session before handing
it to another client.

			regards, tom lane

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