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

On 08/15/2016 12:23 PM, Pavel Stehule wrote:
>
>
> 2016-08-15 12:18 GMT+02:00 Aleksander Alekseev
> <a(dot)alekseev(at)postgrespro(dot)ru <mailto:a(dot)alekseev(at)postgrespro(dot)ru>>:
>
> > The global temporary tables has persistent rows in the catalogue. The
> > mapping to files can be marked as special and real mapping should be
> > only in memory.
> >
> > So the changes in catalogue related to global temporary tables are
> > pretty less frequently.
>
> I'm afraid I still don't get it. Let say I have an application that
> does `CREATE TEMP TABLE xx ; DROP TABLE xx` in every session all the
> time. Naturally there is not only one temp table per session. Could you
> explain please in more detail how exactly do these persistent rows help?
>
>
> when you use global temporary tables, then you create it only once -
> like usual tables.
>
> you don't drop these tables.
>

I share the view that this is a better/simpler solution to the problem.
It will still require virtual (in-memory) tuples for pg_statistic
records, but everything else works pretty much as for regular tables. In
particular there are no problems with dependencies.

The obvious disadvantage is that it requires changes to applications.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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