Ken Tanzer <ken.tanzer@xxxxxxxxx> writes: > Hi. I've solved my practical problems, and I know unknown types are > just bad, but am still curious about why some of these cause errors, > and others don't. > ag_consulting=> SELECT * FROM (SELECT '1'::unknown) foo UNION ALL > SELECT * FROM (SELECT '1'::unknown) bar; > ERROR: failed to find conversion function from unknown to text FWIW, this succeeds in 9.5 and up, as a result of more aggressive application of the rule "coerce an unknown value to text if we cannot find any other interpretation". > ag_consulting=> CREATE TEMP TABLE t1 AS SELECT '1'::unknown; \d t1 > WARNING: column "unknown" has type "unknown" > DETAIL: Proceeding with relation creation anyway. > SELECT 1 > Table "pg_temp_2.t1" > Column | Type | Modifiers > ---------+---------+----------- > unknown | unknown | As of v10, this will produce a table with a column of type text, not type unknown, again as a result of more aggressively forcing unknown to be something else. 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
