From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
---|---|
To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
Cc: | Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Gokulakannan Somasundaram <gokul007(at)gmail(dot)com>, Markus Schiltknecht <markus(at)bluegap(dot)ch>, Gregory Stark <stark(at)enterprisedb(dot)com>, pgsql-hackers list <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Some ideas about Vacuum |
Date: | 2008-01-16 20:52:56 |
Message-ID: | 20080116205256.GL5076@alvh.no-ip.org |
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Lists: | pgsql-hackers |
Heikki Linnakangas escribió:
> I don't think it's going to work too well, though, not without major
> changes at least. What would happen when you restore a PITR backup of just
> one database? Would the other databases still be there in the restored
> cluster? What state would they be in? After restoring one database, and
> doing some stuff on it, could you ever "merge" those changes with the rest
> of the cluster?
Well, a PITR slave, after you change it, cannot be brought in sync with
the master. This is not different.
If you replicate a single database's stream, the other databases should
not be there. My idea is that a slave could request multiple databases'
streams. The ability to do it is needed anyway, to follow both the
basic database stream and the shared stream.
> Mind you, there's more things shared between databases than the shared
> catalogs. clog for example.
Sure --- my original proposal mentioned the use of the shared WAL stream
for global objects (though I didn't mention pg_clog, but surely it had
better be there).
> For more usefulness, we'd need to keep databases more separate from each
> other than we do now. Databases would need to have their own transaction
> counters, for example.
Hmm, why? Perhaps you are right but I don't see the reason.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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