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Re: cheaper snapshots

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Hannu Krosing <hannu(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: cheaper snapshots
Date: 2011-07-28 15:15:30
Message-ID: CA+TgmoZ5hnYzON6D+YimSFCcGfwG9MXw5mJTChZrTr39w5yKug@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, Jul 28, 2011 at 11:10 AM, Hannu Krosing <hannu(at)2ndquadrant(dot)com> wrote:
> My main point was, that we already do synchronization when writing wal,
> why not piggyback on this to also update latest snapshot .

Well, one problem is that it would break sync rep.

Another problem is that pretty much the last thing I want to do is
push more work under WALInsertLock.  Based on the testing I've done so
far, it seems like WALInsertLock, ProcArrayLock, and CLogControlLock
are the main bottlenecks here.  I'm focusing on ProcArrayLock and
CLogControlLock right now, but I am pretty well convinced that
WALInsertLock is going to be the hardest nut to crack, so putting
anything more under there seems like it's going in the wrong
direction.  IMHO, anyway.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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Subject: Re: psql: bogus descriptions displayed by \d+
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