From: | Adam Brusselback <adambrusselback(at)gmail(dot)com> |
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To: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
Subject: | Plan to support predicate push-down into subqueries with aggregates? |
Date: | 2016-03-08 21:38:56 |
Message-ID: | CAMjNa7cYSi8aXe=thZZvuXpwcLUnQHORPNb0YETgUn5z5ZVi1Q@mail.gmail.com |
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Lists: | pgsql-general |
Hi all.
I was wondering if there were any plans to support predicate push-down
optimization for subqueries (and views) with aggregates?
I was recently bit by this, as I had incorrectly assumed that this was an
optimization that was in place, and designed quite a bit around that
assumption, only to get hit with terrible performance when more data got
loaded into the system.
Currently I had to solve the issue by having aggregate tables which store
the data, which is maintained by triggers on IUD. This gets messy quick,
as I have some aggregates which are dependent on 5-6 other tables. I'd
love to be able to just store the logic for calculating aggregates in a
view, and use that at query time instead of having to deal with it like
this.
I have written a test case script that explains the type of queries I am
talking about, and the issues. It's heavily simplified compared to a real
system, but it'll do. Please see attached.
Thanks,
-Adam
Attachment | Content-Type | Size |
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subquery_pushdown.txt | text/plain | 2.4 KB |
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