On Fri, Oct 06, 2017 at 08:51:53PM +0200, Pavel Stehule wrote: > 2017-10-06 20:39 GMT+02:00 Nico Williams <nico@cryptonector.com>: > > On Fri, Oct 06, 2017 at 06:37:57PM +0200, Pavel Stehule wrote: > > > When we talked about this topic, there are two issues: > > > > > > a) probably not too hard issue - some internal data can be in session sys > > > cache. > > > > > > b) the session sys data should be visible on SQL level too (for some > > tools > > > and consistency) - it is hard task. > > > > Can you expand on this? > > If global temporary tables should be effective, then you have not have > modify system catalogue after creating. But lot of processes requires it - > ANALYZE, query planning.
But the nice thing about them is that you need only create them once, so leave them in the catalog. Stats about them should not be gathered nor stored, since they could be different per-session.
Unfortunately one field from pg_class are not static - reltuples should be per session.