Browsing the PostgreSQL 12 release notes I noticed that JIT is now enabled by default. Having not followed PostgreSQL development closely - does this mean that compilation results are now getting cached and compilation is no longer executed separately for each worker thread in a parallel query ?
I don't know, but just want to chime in with my experience with PG-12 and JIT: Execution-time is still way worse then JIT=off for your queries so we'll turn JIT=off until we can mesure performance-gain.
Hm, that's a bummer. So I guess we'll also have to make sure JIT is turned off when upgrading.