Delete duplicates from a table without primary key SQL

gistfile1.sql

   DELETE FROM claim_rates
    WHERE ctid IN (SELECT
        ctid
      FROM (SELECT
        ctid,
        ROW_NUMBER()
        OVER (
        PARTITION BY claim_tag, rate_type, pricing_record_id
        ORDER BY claim_tag, rate_type, pricing_record_id) AS rnum
      FROM claim_rates) t
      WHERE t.rnum > 1);

Documentation here:
http://wiki.postgresql.org/wiki/Deleting_duplicates