Here is a commit that accomplishes this with a configuration parameter. https://github.com/labkey-matthewb/postgres/commit/b1fd99f4deffbbf3db2172ccaba51a34f18d1b1a
On Mon, Sep 28, 2020 at 2:07 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > Timothy Garnett <tgarn...@panjiva.com> writes: > > Is there some way to tell the planner that unless it's guaranteed by a > > constraint or some such it shouldn't guess that the selectivity of a > > filter/anti-join is 1 row (e.g. minimum to consider is 2 rows unless it's > > guaranteed to be 1 row) or somehow otherwise make it more conservative > > around the worst case possibilities. > > There's been some discussion in that area, but it's a hard problem > to solve in general, and especially so if you'd like to not break > a ton of queries that work nicely today. > > regards, tom lane > > >
