> It strikes me that a possibly useful simplification of the idea is a
> lock type that allows HOT updates and not non-HOT ones; or more
> precisely not ones that change any indexed columns --- if the row ends
> up having to go off-page for lack of space, that need not concern us.
While an improvement over the current, that's still more restrictive
than we actually need for FKs. FKs just need to lock the value of the
reference column(s); they don't care if *other* indexes are updated.
Thus, for an RI reference, we care about one and exactly one unique/PK
index on the referenced table.
-- -- Josh Berkus PostgreSQL Experts Inc.
http://www.pgexperts.com