Re: postgres_fdw: perform UPDATE/DELETE .. RETURNING on a join directly

(2018/04/07 4:17), Andres Freund wrote:
> On 2018-03-05 17:07:10 -0500, Tom Lane wrote:
>> Meanwhile, I'm back to wondering what could possibly have affected
>> the planner's estimates, if pg_proc and pg_statistic didn't change.
>> I confess bafflement ... but we've now eliminated the autovacuum-
>> did-it theory entirely, so it's time to start looking someplace else.
>> I wonder if something in the postgres_fdw remote join machinery
>> is not as deterministic as it should be.
>
> I wonder if temporarily changing postgres_fdw's test to specify an extra
> config that installs auto_explain in full aggressiveness (i.e. including
> costs etc) and enables debug3 logging could help narrow this down?

+1 because we cannot deny the possibility that the plan instability is 
caused by such an unexpected behavior of postgres_fdw.

Best regards,
Etsuro Fujita