RE: multiple sessions to create index in parallel support

Max_parallel_workers and max_parallel_maintenance_workers both equal to 32,    one session create one index in a large
tableshow parallel 8 workers,   the other session creating one index in another separate table always in serial. Even
increasemax_parallel_worers and max_parallel_maintenance_workers to 64, still show one is parallel 8 workers, the other
isdone in serial. 

James

-----Original Message-----
From: Tom Lane <tgl@sss.pgh.pa.us>
Sent: Tuesday, June 21, 2022 10:30 PM
To: James Pang (chaolpan) <chaolpan@cisco.com>
Cc: pgsql-admin@lists.postgresql.org
Subject: Re: multiple sessions to create index in parallel support

"James Pang (chaolpan)" <chaolpan@cisco.com> writes:
>    We have a large database that just migrated data from Oracle to Postgres(13.4), after data load. We try to create
indexes,  with only one connection , the create index automatically run in parallel (table size 40G) ,  then we started
twoconnections and each session creating index on large table, but at this time, only 1 session parallel creating
index,the other one creating index in serial. There are enough parallel_workers and memory.  Is that expected ?  only 1
sessionallowed to parallel index creating at the same time ? 

Check your settings for max_parallel_workers and max_parallel_maintenance_workers.

            regards, tom lane