Horton

Re: SSI heap_insert and page-level predicate locks

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Kevin Grittner <Kevin.Grittner@wicourts.gov>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, Dan Ports <drkp@csail.mit.edu>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2011-09-16T18:51:11Z
Lists: pgsql-hackers 
Jeff Davis <pgsql@j-davis.com> writes:
> On Wed, 2011-06-08 at 17:29 -0500, Kevin Grittner wrote:
>> Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote:
>>> AFAICS, the check for page lock is actually unnecessary.

>> Absolutely correct.  Patch attached.

> I like the change, but the comment is slightly confusing.

I've committed this patch with comment rewording along the lines
suggested by Jeff.  I also moved the CheckForSerializableConflictIn call
to just before, instead of just after, the RelationGetBufferForTuple
call.  We no longer have to do it after, since we don't need to know
which buffer to pass, and it should buy some more low-level parallelism
to run the SSI checks while not holding exclusive lock on the eventual
target buffer.

			regards, tom lane