From: Dean Gibson (DB Administrator) <postgresql@mailpen.com>
To: pgsql-performance@lists.postgresql.org <pgsql-performance@lists.postgresql.org>
Subject: Re: AWS forcing PG upgrade from v9.6 a disaster
Date: Sun, 30 May 2021 21:23:43 -0700
Message-ID: <5463af86-9007-1094-78bf-18e54c60edaf@mailpen.com> (raw)
In-Reply-To: <2370D2C6-4D91-4C96-9410-11EFD9954B21@thebuild.com>
References: <88dec70b-eb63-0b72-0b5d-253851ef127b@mailpen.com>
<92cc8563-195f-8727-d887-5f2bb63f231f@mailpen.com>
<2370D2C6-4D91-4C96-9410-11EFD9954B21@thebuild.com>
On 2021-05-30 20:41, Christophe Pettus wrote:
> On May 30, 2021, at 20:07, Dean Gibson (DB Administrator)
> <postgresql@mailpen.com> wrote:
>> The first two JOINs are not the problem, & are in fact retained in my solution. The problem is the third JOIN, where "fips_county" from "County" is actually matched with the corresponding field from the "zip_code" VIEW. Works fine, if you don't mind the performance impact in v10 & above. It has now been rewritten, to be a sub-query for an output field. Voila ! Back to sub-second query times.
> If, rather than a subquery, you explicitly called out the join criteria with ON, did it have the same performance benefit?
I thought that having a "USING" clause, was semantically equivalent to
an "ON" clause with the equalities explicitly stated. So no, I didn't
try that.
The matching that occurred is *exactly *what I wanted. I just didn't
want the performance impact.
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Subject: Re: AWS forcing PG upgrade from v9.6 a disaster
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