Re: Proposed patch for xact-vs-multixact bugs

From: "Simon Riggs" <simon(at)2ndquadrant(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-patches(at)postgreSQL(dot)org>, "Alvaro Herrera" <alvherre(at)alvh(dot)no-ip(dot)org>
Subject: Re: Proposed patch for xact-vs-multixact bugs
Date: 2006-11-18 12:58:51
Message-ID: 1163854731.27956.784.camel@silverbirch.site
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On Thu, 2006-11-16 at 20:23 -0500, Tom Lane wrote:

> We should treat
> exclusive lock held under any of the current backend's subtransactions
> as not to be overridden.

I can't find any clear discussion of this within the docs. I guess if
there were some clear statements on this it would have been uncovered
earlier.

We should say something like "Once a lock has been taken it will be held
until the end of the transaction. Locks obtained after a SAVEPOINT (i.e.
within a subtransaction) will continue to be held even after a RELEASE
SAVEPOINT". Does this also apply if we do a ROLLBACK TO SAVEPOINT?

I'll do some docs for the Concurrency Control section.

Has the same thinking been applied to table level locks also?
LOCK TABLE has same issue maybe?

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com

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