"Mauricio Fernandez A." <mfacontacto(at)ono(dot)com> writes:
> The only strange thing in the query is that ac.potencialpacientes is
> smallint[] (in fact is the only thing with sense I can see in the error
> message) but I am not using the '<' operator as it suggest.
No, but you're trying to GROUP BY ac.potencialpacientes, and in 7.3 the
only way to do grouping is sort/unique.  So you have to be able to sort
the datatype, and 7.3 doesn't have code to do comparison of arrays.
> Can somebody help me?.
Upgrade.  7.3 is pretty ancient anyway.  Quite aside from lack of features,
its performance is poor compared to 8.1.
			regards, tom lane