David Fetter <[EMAIL PROTECTED]> writes: > On Fri, Sep 29, 2006 at 12:53:19PM -0400, Tom Lane wrote: >> In particular, the spec says >> ROW(1,2,NULL) IS NOT NULL >> is false, because the row fields must be *all* not null to make it true.
> That's odd because as I understand the above, > ROW(1,2,NULL) IS NULL > is also false. Have I misunderstood? Yup, they are both false. The spec goes to some trouble to make it clear that IS NULL/IS NOT NULL are not inverses for row values: NOTE 135 - For all R, "R IS NOT NULL" has the same result as "NOT R IS NULL" if and only if R is of degree 1. Table 16, "<null predicate> semantics", specifies this behavior. What I find odd is the lack of comparable language about arrays. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match