Correlated subselect in regression test

Peter Eisentraut <peter_e@gmx.net> writes:

The regression test file subselect.sql contains the following query under the
heading "Correlated subselects":

SELECT '' AS five, f1 AS "Correlated Field"
FROM SUBSELECT_TBL
WHERE (f1, f2) IN (SELECT f2, CAST(f3 AS int4) FROM SUBSELECT_TBL
WHERE f3 IS NOT NULL);

It has been pointed out to me that there is no correlation in this query. Is
there some other special purpose to this query or is it simply categorized
wrongly?

I think it's just mislabeled. Looking at the CVS history, that
particular query hasn't been changed since Tom Lockhart first created
this test back in 6.3. I don't see any reason to think it has a
special purpose in mind.

regards, tom lane