I have been running bisect, it breaks at this commit:
commit 100340e2dcd05d6505082a8fe343fb2ef2fa5b2a Author: Tom Lane <tgl@sss.pgh.pa.us> Date: Sat Jun 18 15:22:34 2016 -0400 Restore foreign-key-aware estimation of join relation sizes. This patch provides a new implementation of the logic added by commit 137805f89 and later removed by 77ba61080. It differs from the original primarily in expending much less effort per joinrel in large queries, which it accomplishes by doing most of the matching work once per query not once per joinrel. Hopefully, it's also less buggy and better commented. The never-documented enable_fkey_estimates GUC remains gone. There remains work to be done to make the selectivity estimates account for nulls in FK referencing columns; but that was true of the original patch as well. We may be able to address this point later in beta. In the meantime, any error should be in the direction of overestimating rather than underestimating joinrel sizes, which seems like the direction we want to err in. Tomas Vondra and Tom Lane Discussion: <31041.1465069446@sss.pgh.pa.us>
On Fri, Jun 24, 2016 at 11:21 AM, Craig Ringer <craig(at)2ndquadrant(dot)com> wrote:
>> I was helping Haroon with this last night. I don't have access to the >> original thread and he's not around so I don't know how much he said. I'll >> repeat our findings here.
Craig, I am around now looking into this. I'll update the list as I get more info.
Apparently my previous message (this same text ) didn't make it through ...
