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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tatsuo Ishii <ishii@postgresql.org>
Cc: mmoncure@gmail.com
Cc: damon@huddler-inc.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Stored procedure declared as VOLATILE => no good optimization is done
Date: Fri, 15 Oct 2010 22:31:34 -0400
Message-ID: <26735.1287196294@sss.pgh.pa.us> (raw)
In-Reply-To: <20101016.104738.1076064300636336418.t-ishii@sraoss.co.jp>
References: <AANLkTik6ynVXSZL9zbAcB12-+S1RfLoNQUGNANTNJjsH@mail.gmail.com>
	<AANLkTin9sD8RCTcFqm1JG2fCLZKpMTZaFDcSDern=3iS@mail.gmail.com>
	<20101016.104738.1076064300636336418.t-ishii@sraoss.co.jp>

Tatsuo Ishii <ishii@postgresql.org> writes:
> So can I say "if a function is marked IMMUTABLE, then it should never
> modify database"? Is there any counter example?
> It seems if above is correct, I can say STABLE functions should never
> modify databases as well.

Both of those things are explicitly stated here:
http://developer.postgresql.org/pgdocs/postgres/xfunc-volatility.html

			regards, tom lane



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