Re: Default setting for enable_hashagg_disk
От | Tomas Vondra |
---|---|
Тема | Re: Default setting for enable_hashagg_disk |
Дата | |
Msg-id | 20200712123043.hnjsluya5mbwhnq4@development обсуждение исходный текст |
Ответ на | Re: Default setting for enable_hashagg_disk (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Sat, Jul 11, 2020 at 08:47:54PM -0400, Tom Lane wrote: >Tomas Vondra <tomas.vondra@2ndquadrant.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. > You're right, I was specifically pushing against that aspect of the proposal. Sorry for not making that clearer, I assumed it's clear from the context of this (sub)thread. I agree making it 1.0 (or equal to work_mem, if it's not a multiplier) by default, but allowing it to be increased if needed would address most of the spilling issues. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
В списке pgsql-hackers по дате отправления: