Hi frederic.yhuel > Thank you. FWIW, I would prefer a sub-linear growth, so maybe something > like this
> vacthresh = Min(vac_base_thresh + vac_scale_factor * reltuples, > vac_base_thresh + vac_scale_factor * pow(reltuples, 0.7) * 100); > This would give : > * 386M (instead of 5.1 billion currently) for a 25.6 billion tuples table ; > * 77M for a 2.56 billion tuples table (Robert's example) ; > * 15M (instead of 51M currently) for a 256M tuples table ; > * 3M (instead of 5M currently) for a 25.6M tuples table. > The other advantage is that you don't need another GUC. Argee ,We just need to change the calculation formula，But I prefer this formula because it calculates a smoother value. vacthresh = (float4) fmin(vac_base_thresh + vac_scale_factor * reltuples,vac_base_thresh + vac_scale_factor * log2(reltuples) * 10000); or vacthresh = (float4) fmin(vac_base_thresh + (vac_scale_factor * reltuples) , sqrt(1000.0 * reltuples)); Frédéric Yhuel <frederic.yh...@dalibo.com> 于2024年8月12日周一 21:41写道： > > > On 8/7/24 23:39, Nathan Bossart wrote: > > I've attached a new patch to show roughly what I think this new GUC > should > > look like. I'm hoping this sparks more discussion, if nothing else. > > > > Thank you. FWIW, I would prefer a sub-linear growth, so maybe something > like this: > > vacthresh = Min(vac_base_thresh + vac_scale_factor * reltuples, > vac_base_thresh + vac_scale_factor * pow(reltuples, 0.7) * 100); > > This would give : > > * 386M (instead of 5.1 billion currently) for a 25.6 billion tuples table ; > * 77M for a 2.56 billion tuples table (Robert's example) ; > * 15M (instead of 51M currently) for a 256M tuples table ; > * 3M (instead of 5M currently) for a 25.6M tuples table. > > The other advantage is that you don't need another GUC. > > > On Tue, Jun 18, 2024 at 12:36:42PM +0200, Frédéric Yhuel wrote: > >> By the way, I wonder if there were any off-list discussions after > Robert's > >> conference at PGConf.dev (and I'm waiting for the video of the conf). > > > > I don't recall any discussions about this idea, but Robert did briefly > > mention it in his talk [0]. > > > > [0] https://www.youtube.com/watch?v=RfTD-Twpvac > > > > Very interesting, thanks! > > >
