On 2019-Jun-10, Robert Haas wrote: > On Fri, Jun 7, 2019 at 6:42 PM Daniel Gustafsson <dan...@yesql.se> wrote:
> > The commit message still refers to it as estimate_rel_size though. The > > comment on > > table_block_relation_estimate_size does too but that one might be > > intentional. > > Oops. New version attached, hopefully fixing those and the compiler > warning Alvaro noted. It does fix the warning, thanks. > > Maybe I’m a bit thick but if the rel is totally empty and without children, > > then curpages as well as relpages would be both zero. But if so, how can we > > enter the second "quick exit” block since curpages by then will be > > increased to > > 10 in the block just before for the empty case? It seems to me that the > > blocks > > should be the other way around to really have a fast path, but I might be > > missing something. > > Well, as you say, I'm just moving the code. I agree that you're just moving the code, but this seems to have been recently broken in 696d78469f37 -- it was correct before that (the heuristic for never vacuumed rels was in optimizer/plancat.c). So in reality the problem that Daniel pointed out is an open item for pg12. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
