Re: AWS forcing PG upgrade from v9.6 a disaster
От | Dean Gibson (DB Administrator) |
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Тема | Re: AWS forcing PG upgrade from v9.6 a disaster |
Дата | |
Msg-id | 5463af86-9007-1094-78bf-18e54c60edaf@mailpen.com обсуждение исходный текст |
Ответ на | Re: AWS forcing PG upgrade from v9.6 a disaster (Christophe Pettus <xof@thebuild.com>) |
Ответы |
Re: AWS forcing PG upgrade from v9.6 a disaster
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Список | pgsql-performance |
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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