On Mon, Feb 29, 2016 at 10:39 AM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> "David G. Johnston" <david.g.johns...@gmail.com> writes: > > On Mon, Feb 29, 2016 at 9:27 AM, Albe Laurenz <laurenz.a...@wien.gv.at> > > wrote: > >> See http://www.postgresql.org/docs/current/static/planner-stats.html > >> "The amount of information stored in pg_statistic by ANALYZE, in > >> particular the > >> maximum number of entries in the most_common_vals and histogram_bounds > >> arrays > >> for each column, can be set on a column-by-column basis using the > >> ALTER TABLE SET STATISTICS command, or globally by setting the > >> default_statistics_target configuration variable." > > > Being able to run ANALYZE on a table in no way implies that I should be > > allowed to run ALTER TABLE SET STATISTICS on the same. > > You're missing the point. If the table owner has *not* run ALTER TABLE > SET STATISTICS, which surely is the typical situation, then whoever runs > ANALYZE can control the volume of stats generated by setting > default_statistics_target locally in his session. Thus, if we allow > non-owners to run ANALYZE, they'd be able to mess things up by setting > the stats target either much lower or much higher than the table owner > expected. ("Much higher" would be bad in a different way than "much > lower", but still bad.) > Yes, this particular implementation detail escaped me at first. I've since posted new thoughts having taking this mis-feature into account. > I imagine this could be addressed by some rule about how if you don't > own the table then your default_statistics_target is overridden by > the global setting, but that would be a mess both conceptually and > implementation-wise. > It seems easy enough to simply disallow session-local changes to this GUC...but barring that this does weigh the decision toward having a GRANT ANALYZE on TABLE since the issue isn't running the ANALYZE but rather its interaction with SET default_statistics_target. An explicit permission allows the table and/or database to choose to provide a user this capability if desired without also requiring the user to become a full-blown owner of the table and thus able to make even bigger and more permanent changes - including altering the default_statistics_target for the table permanently. David J.
