Re: question about parallel. i read document and i can't solve it. provide the solution please.
On Sunday, November 9, 2025, PG Doc comments form 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.
question about parallel. i read document and i can't solve it. provide the solution please.
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
MERGE command is not mentioned in the list of commands for variable substitution
The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/18/plpgsql-implementation.html Description: In the last paragraph of the section 41.11.1. "Variable Substitution" there is such a sentence -- "Variable substitution currently works only in SELECT, INSERT, UPDATE, DELETE, and commands containing one of these..." https://www.postgresql.org/docs/current/plpgsql-implementation.html#PLPGSQL-VAR-SUBST But experiments showed that variable substitution works for MERGE command too.
Re: MERGE command is not mentioned in the list of commands for variable substitution
On Tue, 11 Nov 2025 at 05:52, PG Doc comments form wrote: > "Variable substitution currently works only in SELECT, INSERT, UPDATE, > DELETE, and commands containing one of these..." > https://www.postgresql.org/docs/current/plpgsql-implementation.html#PLPGSQL-VAR-SUBST > But experiments showed that variable substitution works for MERGE command > too. Thanks for the report. You're right that this has been overlooked. The attached patch fixes it. I can take care of this once the back branches are open again after the minor releases are out. David v1-0001-Doc-include-MERGE-in-variable-substitution-comman.patch Description: Binary data
