On Wed, Feb 1, 2017 at 4:38 AM, Merlin Moncure <mmoncure@gmail.com> wrote:
I was just troubleshooting a strange performance issue with pg_trgm (greatest extension over) that ran great in testing but poor in production following a 9.6 in place upgrade from 9.2. By poor I mean 7x slower. Problem was resolved by ALTER EXTENSION UPDATE followed by a REINDEX on the impacted table. Hope this helps somebody at some point :-).
It was probably the implementation of the triconsistent function for pg_trgm (or I would like to think so, anyway).
But if so, the REINDEX should not have been necessary, just the ALTER EXTENSION UPDATE should do the trick. Rebuiding a large gin index can be pretty slow.