On Mon, May 11, 2020 at 5:14 PM Bruce Momjian <br...@momjian.us> wrote: > Agreed. How is this? > > This allows efficient btree indexing of low cardinality columns. > Users upgrading with pg_upgrade will need to use REINDEX to make use > of > this feature.
I still think that the release notes should say that the key is only stored once, while TIDs that identify table rows are stored together as an array. Everything that's helpful (or harmful) about the feature happens as a consequence of that. This isn't hard to grasp intuitively, and is totally in line with how things like Oracle bitmap indexes are presented to ordinary users. -- Peter Geoghegan
