Re: Does RelCache/SysCache shrink except when relations are deleted?

From: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> That's correct. We used to have a limit on the size of catcache
> (if memory serves, it was something like 5000 entries). We got rid of
> it after observing that performance fell off a cliff as soon as you had
> a working set larger than the cache limit. Trust me, if we had a limit,
> you'd still be here complaining, the complaint would just take a
> different form ;-)

Yes, I can imagine. Now I'll believe that caching catalog entries in local
memory without bound is one of PostgreSQL's elaborations for performance.
64-bit computing makes that approach legit. Oracle avoids duplicate catalog
entries by storing them in a shared memory, but that should necessate some
kind of locking when accessing the shared catalog entries. PostgreSQL's
approach, which does not require locking, is better for many-core
environments.

> I concur with Merlin's advice to rethink your schema. 100000 tables is
> far beyond what any sane design could require, and is costing you on
> many levels (I'm sure the OS and filesystem aren't that happy with it
> either).

I agree. I'll suggest that to the customer, too. Thank you very much.

Regards
MauMau