Re: SubtransControlLock and performance problems - Mailing list pgsql-performance

From Tom Lane
Subject Re: SubtransControlLock and performance problems
Date
Msg-id 9908.1581963796@sss.pgh.pa.us
Whole thread Raw
In response to Re: SubtransControlLock and performance problems  (Pavel Stehule <pavel.stehule@gmail.com>)
Responses Re: SubtransControlLock and performance problems  (Pavel Stehule <pavel.stehule@gmail.com>)
List pgsql-performance
Pavel Stehule <pavel.stehule@gmail.com> writes:
> po 17. 2. 2020 v 17:36 odesílatel Laurenz Albe <laurenz.albe@cybertec.at>
> napsal:
>> Either use shorter transactions, or start fewer subtransactions.

> it is interesting topic, but I don't see it in my example

> CREATE OR REPLACE FUNCTION public.fx(integer)
>  RETURNS void
>  LANGUAGE plpgsql
> AS $function$
> begin
>   for i in 1..$1 loop
>   begin
>     --raise notice 'xx';
> exception when others then
>   raise notice 'yyy';
> end;
> end loop;
> end;
> $function$

This example doesn't create or modify any table rows within the
subtransactions, so (I think) we won't assign XIDs to them.
It's consumption of subtransaction XIDs that causes the issue.

            regards, tom lane



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