On Mon, Oct 26, 2020 at 3:08 PM Fabrízio de Royes Mello < fabriziome...@gmail.com> wrote:
> Hi all, > > As you all already know Postgres supports functions in index expressions > (marked as immutable ofc) and for this special index the ANALYZE command > creates some statistics (new pg_statistic entry) about it. > > The problem is just after creating a new index or rebuilding concurrently > (using the new REINDEX .. CONCURRENTLY or the old manner creating new one > and then swapping) we need to run ANALYZE to update statistics but we don't > mention it in any part of our documentation. > > Last weekend Gitlab went down because the lack of an ANALYZE after > rebuilding concurrently a functional index and they followed the > recommendation we have into our documentation [1] about how to rebuild it > concurrently, but we don't warn users about the ANALYZE after. > > Would be nice if add some information about it into our docs but not sure > where. I'm thinking about: > - doc/src/sgml/ref/create_index.sgml > - doc/src/sgml/maintenance.sgml (routine-reindex) > > Thoughts? > > [1] > https://gitlab.com/gitlab-com/gl-infra/production/-/issues/2885#note_436310499 > It would seem preferable to call the lack of auto-analyzing after these operations a bug and back-patch a fix that injects an analyze side-effect just before their completion. It doesn't have to be smart either, analyzing things even if the created (or newly validated) index doesn't have statistics of its own isn't a problem in my book. David J.
