"David G. Johnston" <david.g.johns...@gmail.com> writes: > On Sat, Jul 11, 2020 at 5:47 PM Tom Lane <t...@sss.pgh.pa.us> wrote: >> 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 don't default it to something other than 1.0 we might as well just > make it memory units and let people decide precisely what they want to use > instead of adding the complexity of a multiplier. Not sure how that follows? The advantage of a multiplier is that it tracks whatever people might do to work_mem automatically. In general I'd view work_mem as the base value that people twiddle to control executor memory consumption. Having to also twiddle this other value doesn't seem especially user-friendly. >> 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. > So "your default is 1.0 unless you installed the new database on or after > 13.4 in which case it's 2.0"? What else would be new? See e.g. 848ae330a. (Note I'm not suggesting that we'd change it in a minor release.) regards, tom lane