How to drop multiple interval partitions based on date?

Question

I have a table based on daily partitions.

I can drop a paritition using the below query

ALTER TABLE MY_TABLE DROP PARTITION FOR(TO_DATE('19-DEC-2017','dd-MON-yyyy'))

How can I drop all the partitions (multiple partitions) before 15 days?

Answer 1

You can use PL/SQL like this.

DECLARE
    CANNOT_DROP_LAST_PARTITION EXCEPTION;
    PRAGMA EXCEPTION_INIT(CANNOT_DROP_LAST_PARTITION, -14758);

   ts TIMESTAMP;
BEGIN
   FOR aPart IN (SELECT PARTITION_NAME, HIGH_VALUE FROM USER_TAB_PARTITIONS WHERE TABLE_NAME = 'MY_TABLE') LOOP
      EXECUTE IMMEDIATE 'BEGIN :ret := '||aPart.HIGH_VALUE||'; END;' USING OUT ts;
      IF ts < SYSTIMESTAMP - INTERVAL '15' DAY THEN
      BEGIN
         EXECUTE IMMEDIATE 'ALTER TABLE MY_TABLE DROP PARTITION '||aPart.PARTITION_NAME|| ' UPDATE GLOBAL INDEXES';
      EXCEPTION
            WHEN CANNOT_DROP_LAST_PARTITION THEN
                EXECUTE IMMEDIATE 'ALTER TABLE MY_TABLE SET INTERVAL ()';
                EXECUTE IMMEDIATE 'ALTER TABLE MY_TABLE DROP PARTITION '||aPart.PARTITION_NAME;
                EXECUTE IMMEDIATE 'ALTER TABLE MY_TABLE SET INTERVAL( INTERVAL ''1'' DAY )';            
      END;
      END IF;
   END LOOP;
END;