Re: SSI patch version 14

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: <simon(at)2ndQuadrant(dot)com>,<markus(at)bluegap(dot)ch>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: SSI patch version 14
Date: 2011-02-05 20:43:11
Message-ID: 4D4D61FF020000250003A479@gw.wicourts.gov
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"Kevin Grittner" wrote:

> So now that I'm sure we actually do need code there, I'll add it.

In working on this I noticed the apparent need to move two calls to
PredicateLockTuple a little bit to keep them inside the buffer lock.
Without at least a share lock on the buffer, it seems that here is a
window where a read could miss the MVCC from a write and the write
could fail to see the predicate lock. Please see whether this seems
reasonable:

http://git.postgresql.org/gitweb?p=users/kgrittn/postgres.git;a=commitdiff;h=7841a22648c3f4ae46f674d7cf4a7c2673cf9ed2

> And I'll add the new test to the isolation suite.

We don't need all permutations for this test, which is a good thing
since it has such a long setup time. Is there an easy way to just
run the one schedule of statements on three connections?

-Kevin

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