"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> *The second-level Hash Join combines/sees, in both cases, 7,993 and
> 1,275,138 records but depending on the LEFT/RIGHT order of the sub-nodes
> appears to provide a different result.*
Hmm, that's pretty fishy; and given all the hacking that's gone on lately
on hash join, 9.5 introducing a bug there wouldn't be all that astonishing.
But I decline to try to find it without a self-contained test case.
regards, tom lane