Maximum number of partitions allowed per table.

Question

Interesting findings with interval partitioning:
SQL> SELECT  *
  2    FROM  v$version
  3  /
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for 64-bit Windows: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
SQL> DROP TABLE tbl PURGE
  2  /
Table dropped.
SQL> CREATE TABLE tbl(
  2                   id number(6),
  3                   dt date
  4                  )
  5    PARTITION BY RANGE(dt)
  6      INTERVAL (INTERVAL '1' DAY)
  7      (
  8       PARTITION p1 VALUES LESS THAN (date '-857-12-31')
  9      )
10  /
Table created.
SQL> select  partition_name,
  2          high_value
  3    from  user_tab_partitions
  4    where table_name = 'TBL'
  5  /
PARTITION_NAME HIGH_VALUE
P1             TO_DATE('-0857-12-31 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'N
               LS_CALENDAR=GREGORIAN')
SQL> INSERT
  2    INTO tbl
  3    VALUES(
  4           1,
  5           sysdate
  6          )
  7  /
1 row created.
SQL> DROP TABLE tbl PURGE
  2  /
Table dropped.
SQL> CREATE TABLE tbl(
  2                   id number(6),
  3                   dt date
  4                  )
  5    PARTITION BY RANGE(dt)
  6      INTERVAL (INTERVAL '1' DAY)
  7      (
  8       PARTITION p1 VALUES LESS THAN (date '-858-01-01')
  9      )
10  /
Table created.
SQL> select  partition_name,
  2          high_value
  3    from  user_tab_partitions
  4    where table_name = 'TBL'
  5  /
PARTITION_NAME HIGH_VALUE
P1             TO_DATE('-0858-01-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'N
               LS_CALENDAR=GREGORIAN')
SQL> INSERT
  2    INTO tbl
  3    VALUES(
  4           1,
  5           sysdate
  6          )
  7  /
  INTO tbl
ERROR at line 2:
ORA-14300: partitioning key maps to a partition outside maximum permitted number of partitions
SQL> From Logical Database Limits:
Maximum number of partitions allowed per table or index: 1024K - 1
I always thought limit implies to number of actual, not potential partitions, however it looks like I was wrong, although it makes not much sense to limit potential and not actual partitions:
SQL> select  trunc(sysdate) - date '-858-01-01',
  2          1024 * 1024 - 1
  3    from  dual
  4  /
TRUNC(SYSDATE)-DATE'-858-01-01' 1024*1024-1
                        1048661     1048575
SQL> select  to_char(DATE'-858-01-01' + 1048575,'MM/DD/YYYY')
  2    from  dual
  3  /
TO_CHAR(DA
11/17/2012
SQL> So tomorrow "magic" date should increase by one day. I'll test it. But more interesting if tomorrow I will be able to insert a row that forms a new partition into table TBL.
SY.

Answer 1

rp0428 wrote:
The other argument is that Oracle has to be able to automatically create any partition required and it can only create 1024k - 1. So if you create yours with sysdate how could it create all of the others?Not sure I follow. What is the purpose of counting potential partitions? Partition part# iin sys.tabpart$ is not assigned based on potential partition position. If I issue a DDL to create new partition regardless of interval/non-interval partitioning Oracle has to check how many partitions table has so far or po and raise same/similar exception if partition I am asking to create is over the limit. And, in any case, knowing we can create all potential partitions at table create time doesn't mean I will not try to insert data outside the range. So there is absolutely no guarantee Oracle can automatically create any partition requested. Again, I don't understand why creating non-interval partitioned table with a single initial partition has partition count of 1:
SQL> DROP TABLE tbl1 PURGE
  2  /
Table dropped.
SQL> CREATE TABLE tbl1(
  2                    id number(6),
  3                    dt date
  4                   )
  5    PARTITION BY RANGE(dt)
  6      (
  7       PARTITION p1 VALUES LESS THAN (date '-857-12-31')
  8      )
  9  /
Table created.
SQL> SELECT  partition_count
  2    FROM  user_part_tables
  3    WHERE table_name = 'TBL1'
  4  /
PARTITION_COUNT
              1
SQL>And interval partitioned table with same single initial partition has partition count of 1048575:
SQL> CREATE TABLE tbl1(
  2                    id number(6),
  3                    dt date
  4                   )
  5    PARTITION BY RANGE(dt)
  6      INTERVAL (INTERVAL '1' DAY)
  7      (
  8       PARTITION p1 VALUES LESS THAN (date '-857-12-31')
  9      )
10  /
Table created.
SQL> SELECT  partition_count
  2    FROM  user_part_tables
  3    WHERE table_name = 'TBL1'
  4  /
PARTITION_COUNT
        1048575
SQL> Would be interesting to find out what forces Oracle to go into potential partition mode for interval partitioning.
SY.