Message-ID: <467A95DF.50307@bluegap.ch>
Date: Thu, 21 Jun 2007 17:14:39 +0200
From: Markus Schiltknecht <markus@bluegap.ch>
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To: Andrew Sullivan <ajs@crankycanuck.ca>
CC: pgsql-performance@postgresql.org
Subject: Re: Replication
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	<4676C3A9.7070703@bluegap.ch> <4676CFCB.5070505@emolecules.com>
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Hi,

Andrew Sullivan wrote:
> This isn't quite true.  Slony-II was originally conceived by Jan as
> an attempt to implement some of the Postgres-R ideas.

Oh, right, thanks for that correction.

> Part of the problem, as near as I could tell, was that we had no
> group communication protocol that would really work.  Spread needed a
> _lot_ of work (where "lot of work" may mean "rewrite"), and I just
> didn't have the humans to put on that problem.  Another part of the
> problem was that, for high-contention workloads like the ones we
> happened to be working on, an optimistic approach like Postgres-R is
> probably always going to be a loser.

Hm.. for high-contention on single rows, sure, yes - you would mostly 
get rollbacks for conflicting transactions. But the optimism there is 
justified, as I think most real world transactions don't conflict (or 
else you can work around such high single row contention).

You are right in that the serialization of the GCS can be bottleneck. 
However, there's lots of research going on in that area and I'm 
convinced that Postgres-R has it's value.

Regards

Markus