At Tue, 19 Mar 2019 17:51:32 +0900, Masahiko Sawada <sawada.m...@gmail.com> wrote in <cad21aocuzqmyxrwdw57ejor-j1qrgqm_vrqkokif_ajk4gi...@mail.gmail.com> > On Tue, Mar 19, 2019 at 10:39 AM Haribabu Kommi > <kommi.harib...@gmail.com> wrote: > > The performance results are good. Do we want to add the recommended > > size in the document for the parallel option? the parallel option for > > smaller > > tables can lead to performance overhead. > > > > Hmm, I don't think we can add the specific recommended size because > the performance gain by parallel lazy vacuum depends on various things > such as CPU cores, the number of indexes, shared buffer size, index > types, HDD or SSD. I suppose that users who want to use this option > have some sort of performance problem such as that vacuum takes a very > long time. They would use it for relatively larger tables.
Agree that we have no recommended setting, but I strongly think that documentation on the downside or possible side effect of this feature is required for those who are to use the feature. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
