Gregory Stark wrote:
I guess a generalization of my question is whether the FK-
checking machinery
simply does a SELECT against the referencing column.
It does
Actually the query is (effectively, assuming your equality
operators are named
"=" and the columns match in type)
SELECT 1
FROM ONLY B x
WHERE col1=?
AND col2=?
...
FOR SHARE OF x
Since it has to take a lock on the record found to ensure it
doesn't disappear
before your transaction finishes.
Awesome, this tells me a lot! So I can use EXPLAIN ANALYZE and a
query like this to reason about what indexes I might need on my
foreign key references. Thanks!
- John D. Burger
MITRE
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