Best way to maintain daywise interval partitions in 11g - sql

Question

I had created a sql script in 11g that would drop all partitions having high value less than 60 days in all partitioned tables in the database
DECLARE
TNAME VARCHAR2 (300);
PNAME VARCHAR2 (300);
HIGHVAL VARCHAR2 (3000);
POSITION SMALLINT;
VAL LONG;
CURSOR C1
IS
SELECT TABLE_NAME, PARTITION_NAME, PARTITION_POSITION, HIGH_VALUE
FROM USER_TAB_PARTITIONS
WHERE TABLE_NAME NOT LIKE '%$%'
AND TABLE_NAME NOT LIKE 'BIN%';
BEGIN
OPEN C1;
LOOP
FETCH C1
INTO TNAME, PNAME, POSITION, VAL;
HIGHVAL := VAL;
EXIT WHEN C1%NOTFOUND;
IF TO_DATE (SUBSTR (HIGHVAL, 10, 11), 'RRRR-MM-DD') <
TRUNC (SYSDATE)
- 60
THEN
IF POSITION = 1
THEN
DBMS_OUTPUT.PUT_LINE ('ALTER TABLE ' || TNAME
|| ' SET INTERVAL();'
);
END IF;
DBMS_OUTPUT.PUT_LINE ( 'ALTER TABLE '
|| TNAME
|| ' DROP PARTITION '
|| PNAME
|| ' UPDATE GLOBAL INDEXES PARALLEL 2;'||CHR(10)
|| '--DROPPED'
|| '--'
|| TO_DATE (SUBSTR (HIGHVAL, 10, 11),
'RRRR-MM-DD'
)
);
IF POSITION = 1
THEN
DBMS_OUTPUT.PUT_LINE
( 'ALTER TABLE '
|| TNAME
|| ' SET INTERVAL(NUMTODSINTERVAL(1,''DAY''));'
);
END IF;
END IF;
END LOOP;
COMMIT;
CLOSE C1;
END;
/
I'm executing the generated SQL text
Kindly advice if this correct and any room for enhancement???

Answer 1

A few hints:
It's a perfect place for implicit cursor, so you don't need to manually declare variables, fetch, open & close, ...
Filter high value in the query, earlier is better
Use EXECUTE IMMEDIATE to apply changes instead of manually executing whatever gets printed
You don't need to commit, since it's all DDL
The code:
BEGIN
FOR p IN (SELECT TABLE_NAME, PARTITION_NAME, PARTITION_POSITION, HIGH_VALUE
FROM USER_TAB_PARTITIONS
WHERE TABLE_NAME NOT LIKE '%$%'
AND TABLE_NAME NOT LIKE 'BIN%'
AND TO_DATE (SUBSTR (HIGH_VALUE, 10, 11), 'RRRR-MM-DD') < TRUNC (SYSDATE) - 60)
LOOP
IF p.PARTITION_POSITION = 1
THEN
EXECUTE IMMEDIATE 'ALTER TABLE ' || p.TABLE_NAME || ' SET INTERVAL()';
END IF;
EXECUTE IMMEDIATE 'ALTER TABLE ' || p.TABLE_NAME
|| 'DROP PARTITION ' || p.PARTITION_NAME
|| ' UPDATE GLOBAL INDEXES PARALLEL 2';
IF p.PARTITION_POSITION = 1
THEN
EXECUTE IMMEDIATE 'ALTER TABLE ' || p.TABLE_NAME
|| ' SET INTERVAL(NUMTODSINTERVAL(1,''DAY''));';
END IF;
END LOOP;
END;
/
And a few warnings:
Watch out for UPDATE GLOBAL INDEXES, it does not work with IOT tables (if you use them) (I was wrong with this one)
Watch out for resetting/setting intervals. The general rule is that you can't drop last non-interval partition. Guessing this would be position 1 is risky. Better to rely on user_tab_partitions.interval flag.