Re: Parallel hints in PostgreSQL with consistent perfromance

On Wed, Dec 27, 2023 at 8:15 AM mohini mane <mohini(dot)android(at)gmail(dot)com>
wrote:

> Hello Team,
> I observed that increasing the degree of parallel hint in the SELECT
> query did not show performance improvements.
> Below are the details of sample execution with EXPLAIN ANALYZE
>

PostgreSQL doesn't have hints, unless you are using pg_hint_plan. Which you
should say if you are.

*Output:*
> PSQL query execution with hints 6 for 1st time => 203505.402 ms
> PSQL query execution with hints 6 for 2nd time => 27920.272 ms
> PSQL query execution with hints 6 for 3rd time => 27666.770 ms
> Only 6 workers launched, and there is no reduction in execution time even
> after increasing the degree of parallel hints in select query.
>

All you are showing here is the effect of caching the data in memory. You
allude to changing the degree, but didn't show any results, or even
describe what the change was. Is 6 the base from which you increased, or
is it the result of having done the increase?

Cheers,

Jeff