[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Gnumed-devel] Comments on 0.2
From: |
Karsten Hilbert |
Subject: |
Re: [Gnumed-devel] Comments on 0.2 |
Date: |
Fri, 23 Jun 2006 22:45:10 +0200 |
User-agent: |
Mutt/1.5.11+cvs20060403 |
On Wed, Jun 21, 2006 at 07:44:36PM +1000, Ian Haywood wrote:
> Okay, let's think about this. We all accept the need for XMIN, it's explicit
> locking
> we are querying.
yes
> Imagine two transactions running in parallel. Postgres forces them to
> serialize,
If so configured which we do.
> (randomly if they hit the server at *exactly* the same time)
> Both do
> UPDATE foo SET A=B,C=D WHERE pk=123 and xmin=456;
>
> If we are in read-committed mode, one query sees the result of the other
> (made to wait if necessary),
> and so fails (Cursor.rowcount=0) as xmin doesn't match anymore.
It doesn't "fail", it just updates zero rows - which is just
a nitpick difference but needs to be checked for explicitely.
> In serialisation mode, they don't see each others results, instead one will
> fail
> with a serialisation error, and forced to try again, whereupon it will fail
> (as it has now seen the results of the other)
yes
Karsten
--
GPG key ID E4071346 @ wwwkeys.pgp.net
E167 67FD A291 2BEA 73BD 4537 78B9 A9F9 E407 1346
- Re: [Gnumed-devel] Comments on 0.2......................., (continued)
- Re: [Gnumed-devel] Comments on 0.2......................., Karsten Hilbert, 2006/06/20
- Re: [Gnumed-devel] Comments on 0.2......................., Ian Haywood, 2006/06/20
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/20
- Re: [Gnumed-devel] Comments on 0.2, Tim Churches, 2006/06/20
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/20
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/20
- Re: [Gnumed-devel] Comments on 0.2, Tim Churches, 2006/06/20
- Re: [Gnumed-devel] Comments on 0.2, Ian Haywood, 2006/06/21
- Re: [Gnumed-devel] Comments on 0.2, Tim Churches, 2006/06/21
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/23
- Re: [Gnumed-devel] Comments on 0.2,
Karsten Hilbert <=
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/23
- Re: [Gnumed-devel] Comments on 0.2, Tim Churches, 2006/06/23
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/24
- Re: [Gnumed-devel] Comments on 0.2, Ian Haywood, 2006/06/24
- Re: [Gnumed-devel] Comments on 0.2, Ian Haywood, 2006/06/24
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/24
- Re: [Gnumed-devel] Comments on 0.2, Ian Haywood, 2006/06/24
- Re: [Gnumed-devel] Comments on 0.2, Karsten Hilbert, 2006/06/24
- Message not available
- Re: [Gnumed-devel] errors and middleware (was 0.2), Ian Haywood, 2006/06/24
- Re: [Gnumed-devel] errors and middleware (was 0.2), Karsten Hilbert, 2006/06/24