Re: constrains of array

Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> writes:
>> 2) It should be error in *creation* of table if there is no comparasion
>> operator for constrain check

> Possibly, although it currently doesn't to allow you to add the operator
> after you do the references. The benefits of that might be outweighed by
> the problems if you don't add the operator.

I can't see any good reason not to require the operator to pre-exist.
In fact, there's a good argument that we should require the two columns
to have the exact same datatype. Otherwise, equality may be a pretty
fuzzy concept. Think about varchar vs bpchar comparison, for example
--- shall we consider trailing blanks significant? Which column will
drive the choice?

In any case, it's certainly a bad idea that the system accepted an
FK constraint relating int[] to int.

regards, tom lane