Re: Getting an index scan to be a parallel index scan - Mailing list pgsql-performance

From Justin Pryzby
Subject Re: Getting an index scan to be a parallel index scan
Date
Msg-id 20230201200239.GV22427@telsasoft.com
Whole thread Raw
In response to Re: Getting an index scan to be a parallel index scan  (Alex Kaiser <alextkaiser@gmail.com>)
List pgsql-performance
On Wed, Feb 01, 2023 at 11:22:47AM -0800, Alex Kaiser wrote:
> I've never messed around with extended statistics, but I'm not sure how
> they would help here. From what I've read they seem to help when your query
> is restricting over multiple columns. Since this query is only on one
> column I'm not sure what a good "CREATE STATISTICS ..." command to run
> would be to improve the query plan. Any suggestions?

They wouldn't help.  It seems like that was a guess.

> As for how I found 'force_parallel_mode', I think I found it first here:
> https://postgrespro.com/list/thread-id/2574997 and then I also saw it when
> I was searching for 'parallel' on https://postgresqlco.nf .

Yeah.  force_parallel_mode is meant for debugging, only, and we're
wondering how people end up trying to use it for other purposes.

http://rhaas.blogspot.com/2018/06/using-forceparallelmode-correctly.html

Did you try adjusting min_parallel_index_scan_size /
min_parallel_table_scan_size ?

-- 
Justin



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