Convert time varchar(19) to time::timestamp

convert.sql

ALTER TABLE nextbus RENAME COLUMN time TO time_orig; -- save the old column
ALTER TABLE nextbus ADD COLUMN time timestamp; -- create the new column
UPDATE acrt.nextbus SET time = time_orig::timestamp; -- set the timestamps. This takes a VERY VERY LONG time; for a 395k point table, it took over 654 (!) seconds
ALTER TABLE nextbus DROP COLUMN time_orig;