From: Jan de Visser <jdevisser@digitalfairway.com>
To: Greg Smith <gsmith@gregsmith.com>
Cc: Alvaro Herrera <alvherre@commandprompt.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: I/O on select count(*)
Date: Wed, 14 May 2008 22:38:08 -0400
Message-ID: <1159c1e90805141938j5f85b490rb5c1cfdf9e428bce@mail.gmail.com> (raw)
In-Reply-To: <Pine.GSO.4.64.0805142211300.5617@westnet.com>
References: <920841.71690.qm@web44808.mail.sp1.yahoo.com>
<482B1D5F.EE98.0025.0@wicourts.gov>
<Pine.GSO.4.64.0805142133250.27290@westnet.com>
<20080515020553.GN9838@alvh.no-ip.org>
<Pine.GSO.4.64.0805142211300.5617@westnet.com>
On 5/14/08, Greg Smith <gsmith@gregsmith.com> wrote:
> On Wed, 14 May 2008, Alvaro Herrera wrote:
>
>
> > If neither of the bits is set, then the transaction is either in progress
> (which you can check by examining the list of running transactions in shared
> memory) or your process is the first one to check (in which case, you need
> to consult pg_clog to know the status, and you can update the hint bits if
> you find out a permanent state).
> >
>
> So is vacuum helpful here because it will force all that to happen in one
> batch? To put that another way: if I've run a manual vacuum, is it true
> that it will have updated all the hint bits to XMIN_COMMITTED for all the
> tuples that were all done when the vacuum started?
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To: pgsql-performance@postgresql.org
Cc: jdevisser@digitalfairway.com, gsmith@gregsmith.com, alvherre@commandprompt.com
Subject: Re: I/O on select count(*)
In-Reply-To: <1159c1e90805141938j5f85b490rb5c1cfdf9e428bce@mail.gmail.com>
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