"Dave Page" <dpage(at)vale-housing(dot)co(dot)uk> writes:
> Right, but how can I conditionally join with pg_opclass based on whether
> or not the opclass specified for the column is the default for that
> type?
Check pg_opclass.opcdefault and compare pg_opclass.opcintype to the
index column's datatype (which you'd get from its pg_attribute row
... whether it's an expression is irrelevant).
regards, tom lane