Question

G’day,

How can you select/list all the operator families associated with a database/schema and list all the operations within an operation family in postgreSQL (8.3 if it matters).

Thanks!

Answer 1

Operator families in a schema:

SELECT *
FROM pg_opfamily opf JOIN pg_namespace n ON n.oid = opf.opfnamespace
WHERE n.nspname = 'something';

Getting all the operators within an operator family is more tricky, because an operator families contains some operators directly and some through operator classes that in contains. To get the former, join pg_opfamily with pg_amop, to get the latter, join pg_opfamily with pg_opclass, and then in both cases against pg_operator. It’s questionable how useful this information will be, though, because in order to assess the usability of an operator family for query planning and optimization, you also need information about access methods, data types, and a few other things.