> On Feb 9, 2021, at 10:52 AM, Thorsten Schöning <tschoen...@am-soft.de> wrote:
>
> So, based on which facts does Postgres decide if to use aadditional
> workers or not? Can I see those decisions explained somewhere? I don't
> see anything in the query plan. Thanks!
Hi Thorsten,
This is an interesting topic for me too. here’s a formula for the max number of
workers that Postgres will consider for a table. Of course, most queries use
more than just one table, and I don’t yet understand how Postgres handles the
situation where the formula suggests multiple workers for some tables and a
single worker for others.
There was some conversation about this on the performance mailing list in June.
Here’s a link to the message that contains the formula; there’s more items of
interest in the whole thread:
https://www.postgresql.org/message-id/89423FD3-0F13-447D-8D9E-EB1722150F94%40americanefficient.com
Hope this helps
Philip
