Re: Slightly OT. - Mailing list pgsql-general

From Andrew Sullivan
Subject Re: Slightly OT.
Date
Msg-id 20070601193531.GM24299@phlogiston.dyndns.org
Whole thread Raw
In response to Re: Slightly OT.  ("Alexander Staubo" <alex@purefiction.net>)
Responses Re: Slightly OT.  ("Alexander Staubo" <alex@purefiction.net>)
List pgsql-general
On Fri, Jun 01, 2007 at 08:57:36PM +0200, Alexander Staubo wrote:
> I fail to see how that's an excuse not to replicate DDL. If I run
> "alter table" on the master, there is no reason whatever that this
> command cannot be executed on all the slaves -- which is what I would
> expect of a replication system.

There is a way to replicate the DDL.  A well-documented way.  It's
sort of ugly, I think everyone will admit, but it was the path chosen
because it allowed the entire thing to fit in user space, which meant
it was possible to install it on an unpatched PostgreSQL that was
already deployed in the field.  That's a non-zero benefit.

> I could be wrong, but I believe Slony fails at this because it is
> trigger-based and simply cannot detect DDL changes.

No, there were in fact alternatives (like, for instance, patching the
back end code).  But that was undesirable for the reason I note
above.

A

--
Andrew Sullivan  | ajs@crankycanuck.ca
In the future this spectacle of the middle classes shocking the avant-
garde will probably become the textbook definition of Postmodernism.
                --Brad Holland

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