Re: [CORE] FOR SHARE vs FOR UPDATE locks

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: pgsql-core(at)postgresql(dot)org
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com>, "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, "Simon Riggs" <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [CORE] FOR SHARE vs FOR UPDATE locks
Date: 2006-12-01 18:55:05
Message-ID: 200612011055.06368.josh@agliodbs.com
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Tom,

> So at this point we are facing three options:
>         - throw in a large and poorly tested "fix" at the last moment;
>         - postpone 8.2 until we can think of a real fix, which might
>           be a major undertaking;
>         - ship 8.2 with the same behavior 8.0 and 8.1 had.
> None of these are very attractive, but I'm starting to think the last
> is the least bad.

Yes. If it was earlier in the beta cycle I'd say no, but frankly this
behavior has existed for two years without examples of real-life data
loss. Further, the TPC tests, which are supposed to give ACID properties
a workout, would not break this, so the industry doesn't consider it very
important either.

So, I think it needs to go on the list for 8.2.1 or 8.3 (depending on what
changes the fix requires) but I don't think we should hold up the release.

As PR maven, though, you know I'm biased about the release date.

I would suggest a last-minute doc patch documenting the behavior and
suggesting that locks should always be declared in the outer transaction
prior to any savepoints.

--
--Josh

Josh Berkus
PostgreSQL @ Sun
San Francisco

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