From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@postgresql.org>
cc: pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Rework the pg_statistic_ext catalog
In-reply-to: <8833.1560647898@sss.pgh.pa.us>
References: <E1hcHz2-0005mY-5A@gemulon.postgresql.org>
 <8833.1560647898@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Sat, 15 Jun 2019 21:18:18 -0400"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <20155.1560650744.1@sss.pgh.pa.us>
Date: Sat, 15 Jun 2019 22:05:44 -0400
Message-ID: <20156.1560650744@sss.pgh.pa.us>
Precedence: bulk

I wrote:
> Tomas Vondra <tomas.vondra@postgresql.org> writes:
>> Rework the pg_statistic_ext catalog

> So ... not one of the buildfarm members that are running TAP tests
> likes this. ...
> I think probably what's happening is that pg_dump is still trying to dump
> directly from the catalog, when what it needs to do now is dump from the
> view, in case it's not running as superuser.

I experimented with extracting the required data from the view, and
there are at least two show-stopper problems:

* The view doesn't expose pg_statistic_ext.oid, which pg_dump has to have
for dependency tracking purposes.  I think we could just add it though.
Now that OIDs are ordinary columns it won't even look very odd.

* Rather than just not exposing the critical data for stats you don't
have privilege to read, the view doesn't expose anything at all.
I do not think that's acceptable; it creates a significant hazard of
data loss during pg_dump, for no very good reason.  What we should
be doing, IMO, is still showing all the rows but filling the data-value
columns with nulls in rows where the caller can't access the underlying
data.

			regards, tom lane