| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Manuel Weitzman <manuelweitzman(at)gmail(dot)com> |
| Cc: | David Rowley <dgrowleyml(at)gmail(dot)com>, Jeremy Schneider <schnjere(at)amazon(dot)com>, "pgsql-performance(at)lists(dot)postgresql(dot)org" <pgsql-performance(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: Planning performance problem (67626.278ms) |
| Date: | 2021-06-20 21:06:31 |
| Message-ID: | 1578974.1624223191@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
Manuel Weitzman <manuelweitzman(at)gmail(dot)com> writes:
> I've written a very naive (and crappy) patch to show how adding
> memorization to get_actual_variable_range() could help the planner on
> scenarios with a big number of joins.
So ... the reason why there's not caching of get_actual_variable_range
results already is that I'd supposed it wouldn't be necessary given
the caching of selectivity estimates that happens at the RestrictInfo
level. I don't have any objection in principle to adding another
caching layer if that one's not working well enough, but I think it'd
be wise to first understand why it's needed.
regards, tom lane
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