Hi all, ok this is a silly question, but I've got a doubt: what is the exact meaning of Datum? I see having a look at the macroes (e.g., PG_RETURN_XXX) that a Datum can be used as a pointer or as a single data, that is it can be a reference or a value. Is this right? So for instance the fact that each stored procedure returns a Datum means that the semantic of the Datum is interpreted depending on how the procedure is defined in the SQL language (i.e., it returns a integer, a tuple, ...). Am I right? Moreover, is there a documentation (aside the source code) that explains and links each internal data structure like HeapTuple, HeapTupleHeader, and so on? Thanks, Luca -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general