| From: | Justin Pryzby <pryzby(at)telsasoft(dot)com> |
|---|---|
| To: | Alex Kaiser <alextkaiser(at)gmail(dot)com> |
| Cc: | David Rowley <dgrowleyml(at)gmail(dot)com>, ranier(dot)vf(at)gmail(dot)com, pgsql-performance(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Getting an index scan to be a parallel index scan |
| Date: | 2023-02-01 20:02:39 |
| Message-ID: | 20230201200239.GV22427@telsasoft.com |
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| Lists: | 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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