Re: Determining if two subnets intersect

Florian Weimer <Florian.Weimer@RUS.Uni-Stuttgart.DE> writes:
> Is there some efficient PostgreSQL expression which is true if and
> only if two subnets (given as values of type cidr) have non-empty
> intersection (even if the intersection is not a CIDR network)?

Maybe I'm missing something, but ISTM it's only possible for two
CIDR subnets to overlap if one contains the other.  So you could
check with
    A <<= B OR B <<= A
        regards, tom lane