Re: pgsql: Rework the pg_statistic_ext catalog

On Sun, 16 Jun 2019, 03:05 Tom Lane, <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> I wrote:
> > Tomas Vondra <tomas(dot)vondra(at)postgresql(dot)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.
>
>

Hang on. Isn't the real problem that we should be revoking public access
from pg_statistic_ext_data, not pg_statistic_ext? Normal users should still
be able to see the stats definitions in the catalog table, but not the
stats data, so I think pg_dump wouldn't need changing.

Regards,
Dean

>