>Well, it would obviously be better if PG could figure out it was safe, >but I'm not sure there's a general case where it is. You can see it's OK >because you know there's only one row in your SELECT result-set.
I think, it's OK because NULL can be compared with anything with predictable result and no additional information about types is necessary. Is it correct vision? I agree it's hard to proceed your query with UNION and some sort of error is reasonable here. -- Best regards Ilja Golshtein ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
