From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Ulf Lohbrügge <ulf(dot)lohbruegge(at)gmail(dot)com> |
Cc: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: [PERFORM] Slow execution of SET ROLE, SET search_path and RESET ROLE |
Date: | 2017-12-07 16:01:13 |
Message-ID: | 6684.1512662473@sss.pgh.pa.us |
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Lists: | pgsql-performance |
=?UTF-8?Q?Ulf_Lohbr=C3=BCgge?= <ulf(dot)lohbruegge(at)gmail(dot)com> writes:
> I could reproduce part of the things I described earlier in this thread. A
> guy named Andriy Senyshyn mailed me after reading this thread here (he
> could somehow not join the mailing list) and observed a difference when
> issuing "SET ROLE" as user postgres and as a non-superuser.
This isn't particularly surprising in itself. When we know that the
session user is a superuser, SET ROLE just succeeds immediately.
Otherwise we have to determine whether the SET is allowed, ie, is
the session user a member of the specified role.
It looks like the first time such a question is asked within a session,
we build and cache a list of all the roles the session user is a member
of (directly or indirectly). That's what's taking the time here ---
apparently in your test case, the "admin" role is a member of a whole lot
of roles?
regards, tom lane
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