Re: Difference in execution plans pg12 vs pg14

Thanks to Imre Samu's help, I found out that this is an unwarranted
interference of the JIT compilation. When it is disabled, the short queries
work stably. Before the problem started, I purposely increased the amount
of surrogate data to evaluate performance. Perhaps the logic for enabling
JIT compilation is different in different versions of Postgres. It didn't
show up as clearly on long queries because they were rewritten without JOIN
VIEW and provide filtering before aggregation and linking. I want to make
rougher JIT compiler settings (I think disabling it is fundamentally wrong)
and rewrite all queries similar to long queries. Thanks.
--
Regards, Dmitry!

сб, 11 дек. 2021 г. в 16:18, Peter J. Holzer <hjp-pgsql(at)hjp(dot)at>:

> Is this repeatable or did it just occur once?
>
> 32 µs to retrieve a single row via index probably means that it was
> already cached in RAM
> 842796 µs to retrieve a single row via index doesn't even look realistic
> for a completely cold database on a slow rotating hard disk. If this
> happened only once I suspect that something else interfered (maybe
> another I/O intensive process, if this is on a VM maybe even on another
> guest). If it is repeatable, something very weird is going on.
>
> hp
>
> --
> _ | Peter J. Holzer | Story must make more sense than reality.
> |_|_) | |
> | | | hjp(at)hjp(dot)at | -- Charles Stross, "Creative writing
> __/ | http://www.hjp.at/ | challenge!"
>