Check if a value can be typecast as an interval in postgres
There is a fairly wide variety of formats that produce valid interval input. The simple answer is therefore that you cannot simply check if some string is a valid interval.
Probably the most straightforward solution is to use a PL/pgSQL function that converts the string to interval and returns null on any error:
CREATE FUNCTION string_to_interval(s text) RETURNS interval AS $$BEGIN RETURN s::interval;EXCEPTION WHEN OTHERS THEN RETURN NULL;END; $$ LANGUAGE plpgsql STRICT;Use it like:
SELECT string_to_interval(my_interval) AS my_valid_intervalFROM ...