Truncate partitions older than 2 months - oracle

Question

How to truncate partitions with data older than 2 months?
For an example, i have below table/partition names:
select table_name, partition_name from all_tab_partitions where table_name='TABLENAME';
TABLENAME partitionname1_P30 30
TABLENAME partitionname2_P60 60
TABLENAME partitionname3_P90 90
TABLENAME partitionname4_P120 120
TABLENAME partitionname5_P150 150
TABLENAME partitionname6_P180 180
TABLENAME partitionname7_210 210
TABLENAME partitionname8_P240 240
TABLENAME partitionname9_P270 270
TABLENAME partitionname10_P300 300
TABLENAME partitionname11_P330 330
TABLENAME partitionname12_P360 360
Table is partitioned per month. If we're currently on September, how do I truncate partitions older than 2 months?
Expectation is that only records from Aug-Sep (partitionname8-9) will remain while the rest will be truncated.
CREATE TABLE dbo1.TABLENAME
( PARTITION_ID NUMBER(4, 0) NOT NULL,
TABLE_DATE DATE NOT NULL,
TABLE_TIMESTAMP NUMBER(19, 0) NOT NULL,
TABLE_BUNDLE_ID VARCHAR2(240 BYTE) NOT NULL,
TABLE_TYPE NUMBER(8, 0) NOT NULL,
TABLE_SEVERITY NUMBER(19, 0) NOT NULL,
TABLE_FACILITY NUMBER(19, 0) NOT NULL,
TABLE_HOST VARCHAR2(120 BYTE) NOT NULL,
TABLE_PROCESS VARCHAR2(240 BYTE) NOT NULL,
TABLE_SYSTEM VARCHAR2(240 BYTE) NOT NULL,
TABLE_SESSION_ID VARCHAR2(240 BYTE) NOT NULL,
TABLE_PRINCIPAL VARCHAR2(120 BYTE) NOT NULL,
OBJECT_ID VARCHAR2(120 BYTE),
OBJECT_TYPE VARCHAR2(2 BYTE),
CLIENT_HOST VARCHAR2(120 BYTE),
ACCESS_HOST VARCHAR2(120 BYTE),
SCOPE_ID VARCHAR2(120 BYTE),
STATUS NUMBER(19, 0),
OBJECT_HISTORY NUMBER(19, 0),
TABLE_DETAILS VARCHAR2(4000 BYTE)
)
PARTITION BY RANGE (PARTITION_ID)
(
PARTITION partitionname1_P30 VALUES LESS THAN (30)
,<repeat partition by 30s up to 360, total of 12 partitions>

Answer 1

You can do it like this:
DECLARE
CURSOR PartTables IS
SELECT TABLE_NAME, PARTITION_NAME, HIGH_VALUE
FROM USER_TAB_PARTITIONS
WHERE TABLE_NAME = 'TABLENAME';
highValue TIMESTAMP;
BEGIN
FOR aTab IN PartTables LOOP
EXECUTE IMMEDIATE 'BEGIN :ret := '||aTab.HIGH_VALUE||'; END;' USING OUT highValue;
IF highValue < ADD_MONTHS(SYSDATE, -2) THEN
EXECUTE IMMEDIATE 'ALTER TABLE TABLENAME TRUNCATE PARTITION '||aTab.PARTITION_NAME||' UPDATE INDEXES';
END IF;
END LOOP;
END;
This would work for a RANGE or INTERVAL based partitions, however in this case your requirement is rather useless because you would keep empty partitions for ever. Usually you drop old partitions, for that just replace TRUNCATE by DROP.
In case your partition is base on LIST, i.e. month number the solution would be this:
DECLARE
CURSOR PartTables IS
SELECT TABLE_NAME, PARTITION_NAME, HIGH_VALUE
FROM USER_TAB_PARTITIONS
WHERE TABLE_NAME = 'TABLENAME';
highValue INTEGER;
BEGIN
FOR aTab IN PartTables LOOP
EXECUTE IMMEDIATE 'BEGIN :ret := '||aTab.HIGH_VALUE||'; END;' USING OUT highValue;
IF highValue NOT IN (
EXTRACT(MONTH FROM SYSDATE),
EXTRACT(MONTH FROM ADD_MONTHS(SYSDATE, -1))
)
THEN
EXECUTE IMMEDIATE 'ALTER TABLE TABLENAME TRUNCATE PARTITION '||aTab.PARTITION_NAME||' UPDATE INDEXES';
END IF;
END LOOP;
END;
Based on your strange partition definition, the conditions would be
IF highValue NOT IN (
30*CEIL(TO_CHAR(SYSDATE, 'fmddd')/30),
30*CEIL(TO_CHAR(ADD_MONTHS(SYSDATE, -1), 'fmddd')/30)
)
THEN
but you may run into issues if you run the procedure between 26th - 31st of December.