On Wed, Jun 26, 2019 at 8:05 AM John Lumby <johnlu...@hotmail.com> wrote: > > There is a very recent research paper that discusses the idea of > > varying fillfactor with a view to ameliorating page splits: > > > > Thanks, I am chewing my way through that. As you say, it does address > exactly the issues I raised. > Do you happen to know if their source-code is available somewhere? > ( I did see their db is MS SQL Server but it still might provide some > portable ideas. )
It's just a research paper. It might never be implemented in any system. The point of the paper is to make page splits occur at a steady rate after REINDEX'ing -- not to eliminate or even reduce page splits. > > I suspect that you might find that the enhancements to B-Tree indexes > > that went into Postgres 12 would help with this workload, especially > > if you notice that this happens with indexes that have a lot of duplicates > > > > I had not noticed that, thanks for pointing it out. Yes , in my workload > most of the indexes in question are non-unique and some have very low key > card. I will try out the pg-12 beta when I get a chance. It's easy to show problems with very low cardinality indexes in the old code. You'll definitely notice a difference there. > Is there a pdf or text version? Just the talk slides: https://www.pgcon.org/2019/schedule/attachments/518_nbtree-arch-pgcon.pdf -- Peter Geoghegan
