PostgreSQL SELECT primary key as "serial" or "bigserial"

I've meshed together a way to determine what the data_type is as in the data_type you use in the syntax when creating a new table based off of the PostgreSQL wiki page. If there is something wrong with my query I need to actually know *what* in a given scenario would throw it off on the explicit context of having a query or queries to run on a purely test database/table to modify that database/table so run this query on in order to test for any false-positives. SELECT pg_attribute.attname, format_type(pg_attribute.atttypid, pg_attribute.atttypmod), CASE WHEN format_type(pg_attribute.atttypid, pg_attribute.atttypmod)='bigint' THEN 'bigserial' WHEN format_type(pg_attribute.atttypid, pg_attribute.atttypmod)='integer' THEN 'serial' END AS type FROM pg_index, pg_class, pg_attribute WHERE pg_class.oid = 'delete2'::regclass AND indrelid = pg_class.oid AND pg_attribute.attrelid = pg_class.oid AND pg_attribute.attnum = any(pg_index.indkey) AND indisprimary; Here is a table with a primary key that does not return the primary key with this query: CREATE TABLE delete_key_bigserial ( test1 integer, id bigserial NOT NULL, col1 text, col2 text, test2 integer );