From: | Josh Berkus <josh(at)agliodbs(dot)com> |
---|---|
To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
Cc: | Joel Jacobson <joel(at)gluefinance(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, glue(at)pgexperts(dot)com, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: [Glue] Deadlock bug |
Date: | 2010-08-23 23:07:44 |
Message-ID: | 4C72FF40.10108@agliodbs.com |
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Thread: | |
Lists: | pgsql-hackers |
Kevin,
> In the "for what it's worth" department, I tried out the current
> Serializable Snapshot Isolation (SSI) patch with this test case at
> the SERIALIZABLE transaction isolation level. Rather than defining
> a foreign key, I ran the queries which an SSI implementation in a
> SERIALIZABLE-only environment would -- that didn't use FOR SHARE or
> FOR UPDATE. Not surprisingly, the behavior was the same up to the
> second UPDATE on Process 2, at which point there was no deadlock.
> Process 2 was able to commit, at which point Process 1 failed with:
>
> ERROR: could not serialize access due to concurrent update
Does this happen immediately, not waiting 2 seconds for deadlock checking?
> If you have other examples of "user-hostile" behaviors you want to
> share, I can see how they would behave under an SSI implementation.
> I can almost guarantee that you won't see deadlocks, although you
> will likely see more overall rollbacks in many transaction mixes.
They'd be more variations of this same theme; transactions updating each
other's FKs.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
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