I propose that the B-Tree index item (bottom-up index deletion, "Allow
btree index additions to remove expired index entries to prevent page
splits") link back to the documentation for those that want to drill
down:
https://www.postgresql.org/docs/14/btree-implementation.html#BTREE-DELETION
The same approach was used for the Postgres 13 B-Tree deduplication
release note item (same page from the docs, even).
I understand that it's kind of hard to get the point of the feature
across within the confines of the release notes, which have a very
wide audience. I believe that the practical take-away for more
experienced users should be something like "significantly ameliorates
write-amplification problems in indexes with non-HOT updates". But
that's quite a mouthful. Having a hyperlink to the docs seems like a
sensible compromise. I really just want experienced users to be able
to make the connection between this feature and well-publicized
problems with Postgres index bloat/VACUUM.
Thanks
--
Peter Geoghegan