Re: Row IS NULL question

I wrote:
> Moving makeRowNullTest() doesn't seem like a big deal, but changing
> ExecEvalNullTest would take some added code.  Do we want to tackle that
> during beta, or hold off till 8.3?  An argument for doing it now is that
> we just added nulls-in-arrays in 8.2, and it'd be good if the semantics
> of that were right the first time rather than changing later.

Now that I look more closely, makeRowNullTest() is actually WRONG even
for the cases it handles.  SQL99/SQL2003 define <null predicate> thus:
        1) Let R be the value of the <row value expression>.
        2) If every value in R is the null value, then "R IS NULL" is true;           otherwise, it is false.
        3) If no value in R is the null value, then "R IS NOT NULL" is           true; otherwise, it is false.

makeRowNullTest() is set up to return TRUE for an IS NOT NULL test if
*any* element of R is non null:

regression=# explain select * from int8_tbl x where row(x.q1,x.q2) is not null;
                       QUERY PLAN
-----------------------------------------------------------Seq Scan on int8_tbl x  (cost=0.00..1.05 rows=5 width=16)
Filter:((q1 IS NOT NULL) OR (q2 IS NOT NULL))
 
(2 rows)

So this is clearly a bug and clearly one of long standing --- we've been
getting this wrong since PG 7.3 :-(
        regards, tom lane