Re: [Patch] Temporary tables that do not bloat pg_catalog (a.k.a fast temp tables)

On 2016-08-23 19:18:04 -0300, Claudio Freire wrote:
> On Tue, Aug 23, 2016 at 7:11 PM, Tomas Vondra
> <tomas.vondra@2ndquadrant.com> wrote:
> > Could someone please explain how the unlogged tables are supposed to fix the
> > catalog bloat problem, as stated in the initial patch submission? We'd still
> > need to insert/delete the catalog rows when creating/dropping the temporary
> > tables, causing the bloat. Or is there something I'm missing?

Beats me.


> Wouldn't more aggressive vacuuming of catalog tables fix the bloat?

Not really in my experience, at least not without more drastic vacuum
changes. The issue is that if you have a single "long running"
transaction (in some workloads that can even just be a 3 min taking
query/xact), nothing will be cleaned up during that time. If you have a
few hundred temp tables created per sec, you'll be in trouble even
then. Not to speak of the case where you have queries taking hours (say
a backup).

Andres