From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Add TOAST to system tables with ACL? |
Date: | 2017-10-03 18:19:09 |
Message-ID: | 25039.1507054749@sss.pgh.pa.us |
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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
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