On Tue, Jan 28, 2020 at 2:09 PM Tomas Vondra <tomas.von...@2ndquadrant.com> wrote: > > I agree a separate "leader_id" column is easier to work with, as it does > not require unnesting and so on. > > As for the consistency, I agree we probably can't make this perfect, as > we're fetching and processing the PGPROC records one by one. Fixing that > would require acquiring a much stronger lock on PGPROC, and perhaps some > other locks. That's pre-existing behavior, of course, it's just not very > obvious as we don't have any dependencies between the rows, I think. > Adding the leader_id will change, that, of course. But I think it's > still mostly OK, even with the possible inconsistency.
There were already some dependencies between the rows since parallel queries were added, as you could see eg. a parallel worker while no query is currently active. This patch will make those corner cases more obvious. Should I document the possible inconsistencies?
