> This underfits:
>
> postgres=# select hstore_to_array('a=>1,b=>2,c=>3'::hstore) &&
> hstore_to_array('a=>2,d=>4,b=>2'::hstore)
>
> ...because array overlaps op takes every element (even 'a' or 2 alone)
> and doesn't test for key and value together like in 'b=>2'!
How about hstore_to_matrix? Then you have a tuple for each key/value pair.
Paul