Re: [PATCH] postgres_fdw extension support

On 2015-07-21 07:55:17 -0700, Paul Ramsey wrote:
> On Tue, Jul 21, 2015 at 7:45 AM, Andres Freund <andres@anarazel.de> wrote:
> So, right after reading the options in postgresGetForeignRelSize,
> expand the extension list into a list of all ops/functions, in a
> sorted list, and let that carry through to the deparsing instead?

I'd actually try to make it longer lived, i.e. permanently. And just
deallocate when a catcache callback says it needs to be invalidated;
IIRC there is a relevant cache.

> That
> would happen once per query, right? But the deparsing also happens
> once per query too, yes? Is the difference going to be that big? (I
> speak not knowing the overhead of things like systable_beginscan, etc)

What you have here is an O(nmembers * nexpressions) approach. And each
of those scans is going to do non-neglegible work (an index scan of
pg_depend), that's fairly expensive.

- Andres