On Tue, Jun 06, 2006 at 11:58:45AM -0400, Rod Taylor wrote:
> On Tue, 2006-06-06 at 10:38 -0500, Jim C. Nasby wrote:
> > On Wed, May 31, 2006 at 09:33:04PM +0000, Christopher Browne wrote:
> > > Based on the discussion of the last day or so, we really need to see
> > > about getting version 1.2 released.
> > > 
> > > As far as I can tell, all of the issues Rod pointed out are resolved in
> > > CVS HEAD, so that 1.2 should seriously diminish the need for
> > > "super-skilled staff" when setting up Very Large Instances.  Some issues
> > > do not disappear; there will still be long running transactions that
> > > cause some inconvenience, which is, to a great degree, an unavoidable
> > > problem.  But we can certainly get rid of a bunch of the "misfeature" cases.
> > 
> > There's some ideas in
> > http://archives.postgresql.org/pgsql-hackers/2006-02/msg01164.php that
> > could potentially eliminate the issues associated with long-running
> > transactions, should someone want to push for it. In a nutshell, the
> > idea is to provide a means for a transaction to list a set of tables
> > that it will never touch (again). Vacuum can then take that into account
> > when figuring out what the minimum XID that has to be kept in a table
> > is.
> 
> That doesn't necessarily help by itself unless you can give Slony the
> specific order that you want tables to be initialized in, and even then
> that only helps if there are a small number of hotspots.

Which (at least in my experience) is usually the case. Generally,
long running transactions hurt the most on things like queue tables,
which will bloat up horribly.

If nothing else, Slony could just order things by pg_class.relpages.
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby at pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461