Hi!

Afaiac the join pruning where the outer table is a partitioned table is the 
relevant case.

I am not sure whether there are other cases.
The join pruning, which works great for plain relations since 9.0, falls short 
for partitioned tables, since the optimizer fails to prove uniqueness there.


In practical cases inner and outer tables are almost surely different ones, but 
I reattached a simpler example. It's the one, I came up with back in September.

I've seen this can be a reason to avoid partitioning for the time being, if the 
application relies on join pruning. I think generic views make it almost 
necessary to have it. If you had a different answer in mind, please don't 
hesitate to ask again.


Regards
Arne


________________________________
From: Alvaro Herrera <alvhe...@alvh.no-ip.org>
Sent: Monday, January 17, 2022 7:16:08 PM
To: Arne Roland
Cc: Julien Rouhaud; pgsql-hackers
Subject: Re: missing indexes in indexlist with partitioned tables

Hmm, can you show cases of queries for which having this new
partIndexlist changes plans?

--
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"Saca el libro que tu religión considere como el indicado para encontrar la
oración que traiga paz a tu alma. Luego rebootea el computador
y ve si funciona" (Carlos Duclós)



Attachment: indexlist_to_late.sql
Description: indexlist_to_late.sql

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