Hi, On 2018-06-06 01:06:39 +1200, David Rowley wrote: > On 6 June 2018 at 00:57, Andres Freund <and...@anarazel.de> wrote: > > I think it's ok to only handle this gracefully if serialization is > > supported. > > > > But I think my proposal to continue use a hashtable for the already > > known groups, and sorting for additional groups would largely address > > that largely, right? We couldn't deal with groups becoming too large, > > but easily with the number of groups becoming too large. > > My concern is that only accounting memory for the group and not the > state is only solving half the problem. It might be fine for > aggregates that don't stray far from their aggtransspace, but for the > other ones, we could still see OOM.
> If solving the problem completely is too hard, then a half fix (maybe > 3/4) is better than nothing, but if we can get a design for a full fix > before too much work is done, then isn't that better? I don't think we actually disagree. I was really primarily talking about the case where we can't really do better because we don't have serialization support. I mean we could just rescan from scratch, using a groupagg, but that obviously sucks. Greetings, Andres Freund
