Re: Add TOAST to system tables with ACL?

Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> writes:
> This topic was already discussed (at least one time) in 2011. See [1] for
> details. I'd like to raise that again.

I'm a bit worried about adding a toast table to pg_class, and more so
about pg_database, because both of those have to be accessed in situations
where it's not clear that we could successfully fetch from a toast table,
because too little of the catalog access infrastructure is alive.

pg_class is probably all right as long as only the ACL field could ever
get toasted, since it's unlikely that any low-level accesses would be
paying attention to that field anyway.

For pg_database, you'd have to make sure that the startup-time check of
database CONNECT privilege still works if the ACL's been pushed out of
line.

> Also, I've notice performance degradation of GRANT statements themselves.
> 1000 GRANT statements are executed in 1.5 seconds while 10000 GRANT
> statements are executed in 42 seconds. In average single GRANT statements
> becomes 2.8 times slower. That's significant degradation, but it doesn't
> seem to be fatal degradation for me.

Seems all right, since we could just say "we don't really recommend that
usage pattern".

regards, tom lane