From: Andy Ballingall <andy@areyoulocal.co.uk>
To: 'David Roussel' <pgsql-performance@diroussel.xsmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: 2 phase commit: performance implications?
Date: Wed, 21 Dec 2005 12:10:53 -0000
Message-ID: <20051221121050.ABC559DC804@postgresql.org> (raw)
In-Reply-To: <43A81C8E.6010602@diroussel.xsmail.com>
>Why not just query adjacent databases, rather than copying the data around?
The reasons I didn't choose this way were:
1) I didn't think there's a way to write a query that can act on the data in
two
Databases as though it was all in one, and I didn't want to get into merging
multiple database query results on the Application side. I'd rather just
have all the needed data sitting in a single database so that I can perform
whatever query I like without complication.
2) Most database accesses are reads, and I didn't want a big network
overhead for these, especially since I'm aiming for each database to be
entirely RAM resident.
>If you really wanted to do this, do you need 2pc? Once data has been
uploaded to the database for region A, then asynchronously copy the data to
B, C, D and E later, using a queue.
I've always assumed that my data needed to be consistent. I guess there are
some circumstances where it isn't really a problem, but each would need to
be carefully evaluated. The easy answer is to say 'yes, it must be
consistent'.
>If you try to commit to all at once, then if one fails, then none has the
data.
Yes, I'd prefer things to be that way in any event.
Regards,
Andy
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To: pgsql-performance@postgresql.org
Cc: andy@areyoulocal.co.uk, pgsql-performance@diroussel.xsmail.com
Subject: Re: 2 phase commit: performance implications?
In-Reply-To: <20051221121050.ABC559DC804@postgresql.org>
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