On Mon, Jan 13, 2020 at 05:32:53PM +0100, Tomas Vondra wrote: > On Mon, Jan 13, 2020 at 11:08:40AM +0300, Konstantin Knizhnik wrote: > > > >"if any code tried to access the statistics directly from the table, > >rather than via the caches". > > > >Currently optimizer is accessing statistic though caches. So this > >approach works. If somebody will rewrite optimizer or provide own > >custom optimizer in extension which access statistic directly > >then it we really be a problem. But I wonder why bypassing catalog > >cache may be needed. > > > > I don't know, but it seems extensions like hypopg do it.
AFAIR, hypopg only opens pg_statistic to use its tupledesc when creating statistics on hypothetical partitions, but it should otherwise never reads or need plain pg_statistic rows.
