Horton

Re: 9.2beta1, parallel queries, ReleasePredicateLocks, CheckForSerializableConflictIn in the oprofile

Ants Aasma <ants@cybertec.at>

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From: Ants Aasma <ants@cybertec.at>
To: Merlin Moncure <mmoncure@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Florian Pflug <fgp@phlo.org>, Sergey Koposov <koposov@ast.cam.ac.uk>, Jeff Janes <jeff.janes@gmail.com>, pgsql-hackers@postgresql.org, Stephen Frost <sfrost@snowman.net>
Date: 2012-06-04T15:42:41Z
Lists: pgsql-hackers

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  1. Improve bulk-insert performance by keeping the current target buffer pinned

On Mon, Jun 4, 2012 at 6:38 PM, Merlin Moncure <mmoncure@gmail.com> wrote:
> On Mon, Jun 4, 2012 at 10:17 AM, Merlin Moncure <mmoncure@gmail.com> wrote:
>> What happens (in the very unlikely, but possible case?) if another
>> backend races to the buffer you've pointed at with 'victim'?  It looks
>> like multiple backends share the clock sweep now, but don't you need
>> to need an extra test to ensure it's still a candidate victim buffer?
>
> Actually, I don't think you do: the existing check on refcount is
> probably good enough.  Hm, why did you get rid of
> BufferStrategyControl.lastFreeBuffer?

It was dead code as far as I could tell. That change isn't actually
relevant for this patch because free-list management is still
protected by a lock (except the initial unlocked test that is
doublechecked under lock) and so doesn't need any adjustment.

Ants Aasma
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