Wrong calculation for daily partitions - oracle

Question

Oracle : 11.2.0.2
I'm trying to drop monthy and daily partitions using a script. This works fine for monthly partitions but not for daily partitions. Below is the error I see in the log. Day of the month is becoming zero when calculating.
2013-08-0|SYS_P328538|2|YES
DECLARE
*
ERROR at line 1:
ORA-01847: day of month must be between 1 and last day of month
ORA-06512: at line 43
Here below is the script. I think highvalue date is miscalculated.
SQL> DECLARE
2 CURSOR tab_part_cur IS
3 select PARTITION_POSITION, PARTITION_NAME,HIGH_VALUE,INTERVAL from dba_tab_partitions where table_name = 'MO_USAGEDATA'
and table_owner = 'WSMUSER17'
order by PARTITION_POSITION;
4 tab_part_rec tab_part_cur%ROWTYPE;
5 lHighValue LONG;
6 strPartitionLessThanDate VARCHAR2(100);
7 dtTestDate DATE;
8 DaysInPast NUMBER;
9 SQLstr varchar2(100);
10 strIntervalType varchar2(1000);
11 strRunType varchar2(20);
12 BEGIN
13 strRunType := 'DRY_RUN';
14 select INTERVAL into strIntervalType from dba_part_tables where table_name ='MO_USAGEDATA' and owner = 'WSMUSER17';
15 strIntervalType := REGEXP_SUBSTR(strIntervalType, '''[^'']+''');
16 DBMS_OUTPUT.PUT_LINE(strIntervalType);
17 CASE
18 WHEN strIntervalType = '''DAY''' THEN
19 DBMS_OUTPUT.PUT_LINE('Interval type = '||strIntervalType);
20 -- dtTestDate := CURRENT_DATE - 7 - 1; Offset adjustment if necessary
21 dtTestDate := CURRENT_DATE - 7;
22 DBMS_OUTPUT.PUT_LINE('Test Date = '||dtTestDate);
23 WHEN strIntervalType = '''MONTH''' THEN
24 DBMS_OUTPUT.PUT_LINE('Interval type = '||strIntervalType);
25 -- dtTestDate := CURRENT_DATE - 90;
26 dtTestDate := ADD_MONTHS(current_date,- 7);
27 DBMS_OUTPUT.PUT_LINE('TestDate = '||dtTestDate);
28 ELSE
29 DBMS_OUTPUT.PUT_LINE('Unexpected interval, exiting.');
30 GOTO EXIT;
31 END CASE;
32 OPEN tab_part_cur;
33 LOOP
34 FETCH tab_part_cur INTO tab_part_rec;
35 EXIT WHEN tab_part_cur%NOTFOUND;
36 DBMS_OUTPUT.PUT_LINE(tab_part_cur%ROWCOUNT);
37 lHighValue := tab_part_rec.high_value;
38 /* This next line seems redundant but is needed for conversion quirk from LONG to VARCHAR2
39 */
40 strPartitionLessThanDate := lHighValue;
41 strPartitionLessThanDate := substr(strPartitionLessThanDate, 11, 10);
42 DBMS_OUTPUT.PUT_LINE(strPartitionLessThanDate ||'|'|| tab_part_rec.partition_name ||'|'|| tab_part_rec.partition_position ||'|'|| tab_part_rec.interval);
43 DBMS_OUTPUT.PUT_LINE(TO_DATE(strPartitionLessThanDate, 'YYYY-MM-DD') ||'******'||dtTestDate);
44 IF TO_DATE(strPartitionLessThanDate, 'YYYY-MM-DD') < dtTestDate AND tab_part_rec.partition_name <> 'PART_MINVALUE
' THEN
45 SQLstr := 'ALTER TABLE WSMUSER17.MO_USAGEDATA DROP PARTITION '||tab_part_rec.partition_name ||' update Global indexes';
46 DBMS_OUTPUT.PUT_LINE('Targeted Partition !!!!!!!!');
47 IF strRunType = 'LIVE_RUN' THEN
48 DBMS_OUTPUT.PUT_LINE('Dropping Partition !!!!!!!!');
49 execute immediate SQLstr;
50 END IF;
51 END IF;
52 END LOOP;
53 CLOSE tab_part_cur;
54 << EXIT >>
55 DBMS_OUTPUT.PUT_LINE('Partition purge complete');
56 END;
57 /
'DAY'
Interval type = 'DAY'
Test Date = 03-SEP-13
1
2012-06-1|PART_MINVALUE|1|NO
01-JUN-12******03-SEP-13
2
2013-08-0|SYS_P328538|2|YES
DECLARE
*
ERROR at line 1:
ORA-01847: day of month must be between 1 and last day of month
ORA-06512: at line 43
I'm trying to keep lat 7 partitions in the daily partitioned table and drop the rest of the partitions. But its not dropping them.

Answer 1

Ok, I created the table, inserted some data and ran some of your queries and you've got something wrong with your substring:
SQL> CREATE TABLE "MO_USAGEDATA" (
2 "REQUESTDTS" TIMESTAMP (9) NOT NULL ENABLE
3 )
4 partition by range ("REQUESTDTS") INTERVAL(NUMTODSINTERVAL(1,'DAY'))
5 (partition PART_MINVALUE values less than(TIMESTAMP '2012-06-18 00:00:00'));
Table created
SQL> INSERT INTO MO_USAGEDATA
2 (SELECT SYSDATE + ROWNUM FROM dual CONNECT BY LEVEL <= 30);
30 rows inserted
SQL> SELECT high_value, INTERVAL
2 FROM all_tab_partitions
3 WHERE table_name = 'MO_USAGEDATA'
4 AND table_owner = USER
5 ORDER BY PARTITION_POSITION;
HIGH_VALUE INTERVAL
------------------------------------ ---------
[...]
TIMESTAMP' 2013-09-30 00:00:00' YES
TIMESTAMP' 2013-10-01 00:00:00' YES
TIMESTAMP' 2013-10-02 00:00:00' YES
[...]
SQL> SELECT substr('TIMESTAMP'' 2013-10-02 00:00:00''', 11, 10) FROM dual;
SUBSTR('TIMESTAMP''2013-10-020
------------------------------
2013-10-0
As you can see you're off by one character. It works with DATE columns, but for TIMESTAMP partitionning, you'll need to adjust the offset.