Michael Glaesemann <grzm@xxxxxxxxxxxxx> writes: > ... it appears that one can't directly access the columns of a > composite type when creating an index, i.e., neither UNIQUE (foo.bar) > nor UNIQUE ((foo).bar) work. You need both, ie something like create table foo (bar date_co_interval); create unique index fooi on foo (((bar).from_date)); The outer set of parens is required for any index expression. Basically that's to fix a grammar conflict against the possible presence of an index opclass, that is given create index fooi on foo (x ! y) is that an infix operator expression "x ! y", or a postfix operator expression "x !" followed by an opclass name? The inner set of parens is because "a.b" is always interpreted as a table and column name. To refer to a column, and then qualify it with a composite-type field, we require you to write "(b).c" or "(a.b).c". It'd be legal to write the same index as create unique index fooi on foo (((foo.bar).from_date)); Make sense now? regards, tom lane
