Re: Is FOR UPDATE an optimization fence?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Markus Wanner <markus(at)bluegap(dot)ch>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Is FOR UPDATE an optimization fence?
Date: 2009-10-11 18:00:19
Message-ID: 13522.1255284019@sss.pgh.pa.us
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Markus Wanner <markus(at)bluegap(dot)ch> writes:
> BTW: how do other databases deal with this? Anything of relevance in the
> SQL standards?

SQL99 treats FOR UPDATE as an attribute of DECLARE CURSOR, so there's
no way for it to appear in a sub-select per spec. (In general our
approach to FOR UPDATE is only loosely related to what the spec
thinks it does ...)

regards, tom lane

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