Thread: JIT in PostgreSQL 12 ?

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 ?

Cheers,
Tobias

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 ?

--

Andreas Joseph Krogh

CTO / Partner - Visena AS

Mobile: +47 909 56 963

andreas@visena.com

www.visena.com

På onsdag 29. mai 2019 kl. 10:02:50, skrev Tobias Gierke <tobias.gierke@code-sourcery.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 ?

 

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.

Thanks,
Tobias

Hi,

På onsdag 29. mai 2019 kl. 10:02:50, skrev Tobias Gierke <tobias.gierke@code-sourcery.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 ?

 

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.

--

Andreas Joseph Krogh

CTO / Partner - Visena AS

Mobile: +47 909 56 963

andreas@visena.com

www.visena.com

On 5/29/19 10:02 AM, Tobias Gierke wrote:
> 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 ?

No, the compilation still happens once for each worker. PostgreSQL 12 
includes some smaller performance improvements for the JIT but nothing 
big like that.

Andreas

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.gierke@code-sourcery.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