Re: Default setting for enable_hashagg_disk

Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> writes:
> I don't know, but one of the main arguments against simply suggesting
> people to bump up work_mem (if they're hit by the hashagg spill in v13)
> was that it'd increase overall memory usage for them. It seems strange
> to then propose a new GUC set to a default that would result in higher
> memory usage *for everyone*.

It seems like a lot of the disagreement here is focused on Peter's
proposal to make hash_mem_multiplier default to 2.0. But it doesn't
seem to me that that's a critical element of the proposal. Why not just
make it default to 1.0, thus keeping the default behavior identical
to what it is now?

If we find that's a poor default, we can always change it later;
but it seems to me that the evidence for a higher default is
a bit thin at this point.

regards, tom lane