"Ian Sillitoe" <ian.sillitoe@googlemail.com> writes:
> Thanks for the reply - after a bit more poking around it seems that:
> t1.col IS NOT DISTINCT FROM t2.col
> should work - although I guess this means an upgrade from 8.1 to 8.3
Note that while this will give you the right answers, it will probably
be dog-slow because the planner has exactly zero intelligence about it.
You'd be much better advised to reconsider your table design and get
rid of the assumption that NULLs should be considered "equal".
regards, tom lane