On 2021-05-30 20:41, Christophe Pettus wrote:
On May 30, 2021, at 20:07, Dean Gibson (DB Administrator) <postgre...@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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