Re: Postgres Optimizer ignores information about foreign key relationship, severly misestimating number of returned rows in join

"Ehrenreich, Sigrid" <Ehrenreich@consist.de> writes:
> A patch would be very much appreciated.
> We are currently running on Version 12, but could upgrade to 13, if necessary.
> Could you send me a notification if you managed to program a patch for that?

I've pushed a patch for this to HEAD, but current thinking is that we
will not be back-patching it.  Still, if you're desperate you could
consider running a custom build of v13 with that patch --- a quick
check suggests that it would back-patch easily.  v12 would be a
slightly harder lift (I see one hunk doesn't apply) but probably
not by much.

https://git.postgresql.org/gitweb/?p=postgresql.git;a=patch;h=ad1c36b0709e47cdb3cc4abd6c939fe64279b63f

            regards, tom lane