| From: | Alexander Stoddard <alexander(dot)stoddard(at)gmail(dot)com> |
|---|---|
| To: | Michael Lewis <mlewis(at)entrata(dot)com> |
| Cc: | "pgsql-generallists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org>, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, Thomas Kellerer <shammat(at)gmx(dot)net> |
| Subject: | Re: Accounting for between table correlation |
| Date: | 2021-01-19 22:03:53 |
| Message-ID: | CADDNc-CA0Y=1Urh3nLGy8nZf7V8cDrHcD1V6dpgzfLkJsPtz=w@mail.gmail.com |
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| Lists: | pgsql-general |
On Tue, Jan 19, 2021 at 2:47 PM Michael Lewis <mlewis(at)entrata(dot)com> wrote:
> On Fri, Jan 15, 2021 at 3:27 PM Alexander Stoddard <
> alexander(dot)stoddard(at)gmail(dot)com> wrote:
>
>> I am doing nothing to specify the optimizer. Do I have configurable
>> options in that regard? I was unaware of them.
>>
>
> Read up on join_collapse_limit and geqo.
>
> https://www.postgresql.org/docs/current/runtime-config-query.html
>
> Note that you can set these values within your session to check and even
> just run explain [query] to check if the plan that would be used varies.
>
Thank you for this. I can get different plans by changing the different
parameters, but if the output of EXPLAIN VERBOSE tells me geqo planning
specifically is being used I'm not seeing it. Is there a way to see in the
explain plan if geqo was used?
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