Re: Performance degradation if query returns no rows and column expression is used after upgrading to 12

[Pavel Stehule <pavel.stehule@xxxxxxxxx>]

út 7. 4. 2020 v 19:09 odesílatel Andrus <kobruleht2@xxxxxx> napsal:

Hi!

>on your query there is too slow JIT. Is strange how much. So the best way is disable JIT probably

>set jit to off;

>or same field in postgresql.conf

 

Thank you.

 

set jit to off 

 

makes select fast.

I have encountered this issue only in this query in one database

 

There is  variation of this query running with diferent data in different database in same Debian 10 server. It works fast.

Should I disable jit only for this query or in postgresql.conf permanently?

you can do it in session

SET jit to off;

SELECT ..

SET jit to DEFAULT;

It is really strange why it is too slow. Can you prepare test case? Looks like bug (maybe not Postgres's bug)

Pavel

 

Andrus.