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* question about parallel. i read document and i can't solve it. provide the solution please.
@ 2025-11-10 00:56 PG Doc comments form <[email protected]>
0 siblings, 1 reply; 2+ messages in thread
From: PG Doc comments form @ 2025-11-10 00:56 UTC (permalink / raw)
To: [email protected]; +Cc: [email protected]
The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/18/when-can-parallel-query-be-used.html
Description:
I'm inquiring because I have some problem getting parallel processing to run
effectively in PostgreSQL.
My current parameter settings.
max_parallel_apply_workers_per_subscription = 2
max_parallel_maintenance_workers = 8
max_parallel_workers = 8
max_parallel_workers_per_gather = 4
max_worker_processes = 8
We are using a 4core CPU. When I set the table's parallel_workers to 8 or
use a hint like /* + Parallel (a 8) */, the EXPLAIN ANALYZE output shows: ->
Gather immediately followed by Workers Planned: 8 and Workers Launched: 2.
It seems the performance is not different when I use parallel because the
Workers Launched value is only 2.
How can I increase the Workers Launched value to match the Workers Planned
value, or at least raise it to 4?
I want to use parallel to speed up for index creation and data insertion
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: question about parallel. i read document and i can't solve it. provide the solution please.
@ 2025-11-10 12:05 David G. Johnston <[email protected]>
parent: PG Doc comments form <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: David G. Johnston @ 2025-11-10 12:05 UTC (permalink / raw)
To: [email protected] <[email protected]>; [email protected] <[email protected]>
On Sunday, November 9, 2025, PG Doc comments form <[email protected]>
wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/18/when-can-parallel-
> query-be-used.html
> Description:
>
> I'm inquiring because I have some problem getting parallel processing to
> run
> effectively in PostgreSQL.
This is not the right place to seek support. We have a -general mailing
list for that.
>
> How can I increase the Workers Launched value to match the Workers Planned
> value, or at least raise it to 4?
That level of control is not provided.
>
> I want to use parallel to speed up for index creation and data insertion
>
This page clearly states that data writing is not parallelized.
David J.
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