Keith Rarick <kr@xxxxxx> writes: > I recently did the following: > kr=# alter table t alter u type text[]; > ALTER TABLE > Time: 5.513 ms > Now I'd like to put it back the way it was, but my attempts didn't work: > kr=# alter table t alter u type uuid[]; > ERROR: column "u" cannot be cast automatically to type uuid[] > HINT: Specify a USING expression to perform the conversion. > Time: 0.244 ms It wants you to do this: alter table t alter u type uuid[] using u::uuid[]; The original command worked without a USING because anything-to-text is considered an allowable assignment coercion; but the other way around requires an explicit cast. > kr=# alter table t alter u type uuid[] using array_to_string(u,','); > ERROR: column "u" cannot be cast automatically to type uuid[] > HINT: Specify a USING expression to perform the conversion. > Time: 0.321 ms > (Interestingly, postgres seems to think I don't even have a USING clause > here. Could there be some optimization that removed it?) No, the error message is just worded carelessly; it's the same whether or not you said USING. Probably when there's a USING it needs to be worded more like ERROR: result of USING clause cannot be cast automatically to type uuid[] regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
