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Re: PostgreSQL clustering VS MySQL clustering

From: Christopher Browne <cbbrowne(at)ca(dot)afilias(dot)info>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: PostgreSQL clustering VS MySQL clustering
Date: 2005-01-28 19:49:29
Message-ID: 60k6pxcp12.fsf@dba2.int.libertyrms.com (view raw or flat)
Thread:
Lists: pgsql-performance
ajs(at)crankycanuck(dot)ca (Andrew Sullivan) writes:
> On Mon, Jan 24, 2005 at 01:28:29AM +0200, Hannu Krosing wrote:
>> 
>> IIRC it hates pg_dump mainly on master. If you are able to run pg_dump
>> from slave, it should be ok.
>
> For the sake of the archives, that's not really a good idea.  There
> is some work afoot to solve it, but at the moment dumping from a
> slave gives you a useless database dump.

That overstates things a tad; I think it's worth elaborating on a bit.

There's a problem with the results of dumping the _schema_ from a
Slony-I 'subscriber' node; you want to get the schema from the origin
node.  The problem has to do with triggers; Slony-I suppresses RI
triggers and such like on subscriber nodes in a fashion that leaves
the dumped schema a bit broken with regard to triggers.

But there's nothing wrong with the idea of using "pg_dump --data-only"
against a subscriber node to get you the data without putting a load
on the origin.  And then pulling the schema from the origin, which
oughtn't be terribly expensive there.
-- 
"cbbrowne","@","ca.afilias.info"
<http://dev6.int.libertyrms.com/>
Christopher Browne
(416) 673-4124 (land)

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