Re: Temporary tables under hot standby

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Noah Misch <noah(at)leadboat(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Temporary tables under hot standby
Date: 2012-04-26 06:37:02
Message-ID: 4F98ED0E.6040603@enterprisedb.com
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On 25.04.2012 18:49, Robert Haas wrote:
> Maybe this is a silly idea, but if you're thinking about creating a
> local XID space and a global XID space, it might be a good idea to
> also make allowance for an "unlogged" XID space - that is, an XID
> space that is global to all backends but need not survive crashes.
> This would potentially allow unlogged tables to be used in HS mode. I
> would expect that you probably don't want to go as far as actually
> trying to make this work as part of your current project, but maybe as
> you're structuring the code it would be worth considering the
> possibility that we'll eventually want>2 XID spaces, either for this
> or other reasons.

It would also be nice to have a separate XID space for each database in
the cluster (plus one for global tables). Then one database consuming a
lot of XIDs would not force anti-xid wraparound in other databases, and
it would take us one step closer to being able to (physically)
backup/restore/replicate a single database in a cluster.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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