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pgsql: Fix corner case in cleanup of transactions using SSI.

From: Heikki Linnakangas <heikki(dot)linnakangas(at)iki(dot)fi>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Fix corner case in cleanup of transactions using SSI.
Date: 2012-01-18 16:01:53
Message-ID: E1RnXxR-00039H-4V@gemulon.postgresql.org (view raw or flat)
Thread:
Lists: pgsql-committers
Fix corner case in cleanup of transactions using SSI.

When the only remaining active transactions are READ ONLY, we do a "partial
cleanup" of committed transactions because certain types of conflicts
aren't possible anymore. For committed r/w transactions, we release the
SIREAD locks but keep the SERIALIZABLEXACT. However, for committed r/o
transactions, we can go further and release the SERIALIZABLEXACT too. The
problem was with the latter case: we were returning the SERIALIZABLEXACT to
the free list without removing it from the finished list.

The only real change in the patch is the SHMQueueDelete line, but I also
reworked some of the surrounding code to make it obvious that r/o and r/w
transactions are handled differently -- the existing code felt a bit too
clever.

Dan Ports

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/326b922e8b2d65257a635b5f80e5de0f15dffd3a

Modified Files
--------------
src/backend/storage/lmgr/predicate.c |   26 +++++++++++++++++++++++---
1 files changed, 23 insertions(+), 3 deletions(-)

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