> It still says I lack the secret sauce...
> ERROR: could not implement recursive UNION
> DETAIL: All column datatypes must be hashable.
UNION will preferentially glom onto the btree equality operator, if memory
serves. If that isn't also the hash equality operator, things won't work
pleasantly.
So… what does that mean for types that have both btree and hash equality operators? Don’t all the built-ins also have this problem?