Re: Sv: JIT in PostgreSQL 12 ?

On Wed, May 29, 2019 at 10:48:19AM +0200, Andreas Joseph Krogh wrote:
> På onsdag 29. mai 2019 kl. 10:02:50, skrev Tobias Gierke <tobias(dot)gierke(at)code-sourcery(dot)de>
> Hi,
>
> 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 ?

Thanks for starting the conversation.

> 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.

That's also been my consistent experience and conclusion.

I gather the presumption has been that JIT will be enabled by default..
..but perhaps this is a "Decision to Recheck Mid-Beta" (?)

Justin