oracle Interval 分区维护与管理要点

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Interval Partitioning Essentials - Common Questions - Top Issues (Doc ID 1479115.1

In this Document

Purpose

Questions and Answers

What is interval partitioning?

Where can i find examples?

Can i specify interval partitioning at subpartition level?

Are there any restrictions for the partition key (e.g. data type)?

Can i have Domain Index on an interval partitioned table?

How to specify/change the tablespace storage for the interval partitions

What will be the names of the automatically created interval partitions?

What happens if i want to set a new interval for the table?

How to perform Partition Maintenance Operations (PMOP)?

Exchanging a Partition of an Interval Partitioned Table

Dropping interval partition

Merging partitions

Splitting interval partition

Renaming interval partition

How to disable / turn off interval partitioning for a table?

Partition Count/Pruning

Can i specify NULL value for the partitioning key column?

Why the system generated interval partitions are missing from the DDL of the table when i retrieve it with the function DBMS_METADATA.GET_DDL?

Can interval partitioned table be a parent table for reference partitioning?

References

Applies to:

Oracle Database - Enterprise Edition - Version 11.1.0.6 to 12.1.0.2 [Release 11.1 to 12.1]

Information in this document applies to any platform.

Purpose

To answer common questions, to provide directions to readers to the relevant information related to interval partitioning.

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Questions and Answers

What is interval partitioning?

Interval partitioning is new feature introduced in version 11.1. This feature makes it possible to get the corresponding partitions created automatically as data comes in for the corresponding partition. Before the interval partition feature became available often a maxvalue partition was created to avoid the ORA-14400: inserted partition key does not map to any partition, and time to time the max partition was split into 2 partition to reduce the catch all maxvalue partition.

As an extension of range partitioning the interval partitioning instructs the database to automatically create partitions of a specified interval when data inserted into the table exceeds all of the existing range partitions. You must specify at least one range partition. The range partition key value determines the high value of the range partitions, which is called the transition point, and the database creates interval partitions for data with values that are beyond that transition point. The lower boundary of every interval partition is the non-inclusive upper boundary of the previous range or interval partition.

See also Document 805976.1 11g New Features:INTERVAL PARTITIONING

Where can i find examples?

Interval partitioning can be specified at creation time of the table or it can be set for an existing range partitioned table.

CREATE TABLE

...

PARTITION BY RANGE (<partition key>)

INTERVAL(<number or interval expression>) [STORE IN (<tablespace list>)]

...

(

PARTITION <partition name> ... ---> definition of range partition(s)

...

);

In order to turn an existing range partitioned table into interval partitioned table, execute the following command:

ALTER TABLE <table_name> SET INTERVAL (<number or interval expression>);

You can find examples for interval partitioned tables in the following sources.

Knowledge documents:

Document 854332.1 How To Introduce Interval Partitioning into a Range Partitioned Table
Document 757754.1 Interval Partitioning By Week
Document 1514047.1 How to Build an INTERVAL PARTIONED Table using a NUMBER datatype for the INTERVAL Partition.
Document 466352.1 11g Feature: Interval Partitioning Example

Oracle by Example (ObE) documents:

Understand and Use Interval Partitioning
Using Interval Partitioning

Manipulating Partitions in Oracle Database 11g - Interval partitioning

MOS Database DataWarehousing document:

Example for Interval partitioning - new feature in 11g

See also Interval Literals in the Oracle Database SQL Language Reference.

Can i specify interval partitioning at subpartition level?

No, interval partitioning cannot be specified at subpartition level. There is an enhancement logged to allow this feature at subpartition level.

If you attempt doing that you may get error ORA-00922: missing or invalid option.

This is documented in 11.2 documentation (Oracle Database SQL Language Reference at CREATE TABLE):

"Restrictions on Interval Partitioning

...

Interval partitioning is not supported at the subpartition level."

Are there any restrictions for the partition key (e.g. data type)?

Yes. You can only specify one partitioning key column, and it must be of NUMBER or DATE type.

The TIMESTAMP data type is an extension of the DATE data type, and taking into account the general restrictions on Partitioning Key Columns columns of TIMESTAMP or TIMESTAMP WITH LOCAL TIME ZONE can be used in the partitioning key (TIMESTAMP WITH TIME ZONE not).

Refer to Oracle® Database VLDB and Partitioning Guide - Chapter 2 Partitioning Concepts (e.g. for 11.2):

"When using interval partitioning, consider the following restrictions:

* You can only specify one partitioning key column, and it must be of NUMBER or DATE type."

Oracle Database SQL Language Reference at CREATE TABLE (e.g. for 11.2):

"...Restriction on Partitioning Key Columns

The columns in the column list can be of any built-in data type except

ROWID, LONG, LOB, XMLType, or TIMESTAMP WITH TIME ZONE.

However, columns of TIMESTAMP or TIMESTAMP WITH LOCAL TIME ZONE can be used in the partitioning key.

..."

If you attempt to use varchar2 column for the partition key, then you may get ORA-14037: partition bound of partition "string" is too high

or ORA-14751: Invalid data type for partitioning column of an interval partitioned table (for the latter see Note 1635063.1).

Can i have Domain Index on an interval partitioned table?

In 11g Domain Index is not supported on an interval partitioned table. Trying to create domain index on interval partitioned table results in error ORA-14762: Domain index creation on interval partitioned tables is not permitted, which is expected. ALTER TABLE SET INTERVAL (..) command, that introduces interval partitioning on a range partitioned table may leave existing domain index unnoticed, this is bug 16811830.

In 12 Domain Index is supported on an interval partitioned table, hence you do not get the above mentioned error.

How to specify/change the tablespace storage for the interval partitions

The optional STORE IN part of the INTERVAL clause is for specifying which tablespaces the interval partitions should be created. If a list of tablespaces are specified, then the intervals partitions get created on those tablespaces in a round robin fashion:

INTERVAL(<number of interval expression>) STORE IN (<tablespace list>)

Round Robin according to the logical interval partitions not according to the interval partitions physically realized. See Note 1552239.1 Placement Into Tablespaces of Interval Partitions Are Not Round Robin.

See more information in the following knowledge documents:

Document 874374.1 How to change the tablespace storage of the INTERVAL-PARTITIONED table
Document 1329950.1 Ability to define Tablespace with INTERVAL PARTITION Based on the Value of the Partition Key

For interval partitions that have been created already, you can use the following command to move it into a particular tablespace:

ALTER TABLE <table name> MOVE PARTITION <partition name> TABLESPACE <tablespace name>;

The STORE IN (<tablespace list>) clause does not accept storage parameters, Oracle considers default parameters set for table or for tablespace when creates interval partitions.

For example, interval partitions (SYS_P12016, SYS_P12017, SYS_P12018) are created with 8MB (default) initial extent size in 11.2.0.2 and above unless table default attribute is set differently

dba_segments:

SEGMENT_NA PARTITION_NAME INITIAL_EXTENT in KB TABLESPACE_NAME

---------- ------------------------- -------------------- -------------------------

T_PART P_200105 8192 USERS

T_PART P_200106 8192 USERS

T_PART SYS_P12016 8192 EXAMPLE

T_PART SYS_P12017 8192 EXAMPLE

T_PART SYS_P12018 8192 EXAMPLE

SQL> alter table t_part modify default attributes storage(initial 64k);

Table altered.

SQL> insert into t_part select time_id, CHANNEL_ID, amount_sold from sales where time_id between to_date('04-JUL-2001') and to_date('07-JUL-2001');

1691 rows created.

SQL> commit;

Commit complete.

dba_segments:

SEGMENT_NA PARTITION_NAME INITIAL_EXTENT in KB TABLESPACE_NAME

---------- ------------------------- -------------------- -------------------------

T_PART P_200105 8192 USERS

T_PART P_200106 8192 USERS

T_PART SYS_P12016 8192 EXAMPLE

T_PART SYS_P12017 8192 EXAMPLE

T_PART SYS_P12018 8192 EXAMPLE

T_PART SYS_P12019 64 EXAMPLE

T_PART SYS_P12020 64 EXAMPLE

T_PART SYS_P12021 64 EXAMPLE

T_PART SYS_P12022 64 EXAMPLE

9 rows selected.

What will be the names of the automatically created interval partitions?

The names of the interval partitions created by the database will be system generated names.

You can see the partition names by querying the dba_tab_partitions view or its variants:

Table PARTITION_NAME HIGH_VALUE

----------------- ------------------------- -------------------------------

...

T_PART SYS_P5793 TIMESTAMP' 2001-07-03 00:00:00'

T_PART SYS_P5794 TIMESTAMP' 2001-07-04 00:00:00'

Currently it is not possible to specify a mask or template for partition names, but the system generated name can be renamed, see partition maintenance section of this note for further information.

What happens if i want to set a new interval for the table?

You just alter table with the new interval setting.

e.g. you can change the interval in the following way:

ALTER TABLE t_part SET INTERVAL(NUMTODSINTERVAL(1,'DAY'));

Indexes are not made unusable due to the above operation.

Please note this operation will turn all existing interval partitions to range partitions, and move the transition point to the highest bound.

The following example illustrates this.

SH@dw24> create table t_part (

2 col_date date,

3 col_number number(10))

4 PARTITION BY RANGE (col_date)

5 interval (NUMTOYMINTERVAL(1,'MONTH'))

6 (

7 PARTITION P_200105 VALUES LESS THAN (TO_DATE('2001-06-01', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN')),

8 PARTITION P_200106 VALUES LESS THAN (TO_DATE('2001-07-01', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'))

9 )

10 ;

Table created.

SH@dw24>

SH@dw24> insert into t_part values (TO_DATE('2001-07-05', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> insert into t_part values (TO_DATE('2001-08-07', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> insert into t_part values (TO_DATE('2001-09-08', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> insert into t_part values (TO_DATE('2001-09-11', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> commit;

Commit complete.

SH@dw24>

SH@dw24> -- 3 interval partitions created after the above 4 rows inserted, 1 interval partition for each month 07,08,09 (INTERVAL column is YES).

SH@dw24> select table_name, partition_name, partition_position part_pos,interval,high_value from user_tab_partitions where table_name = 'T_PART' order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INTERVAL HIGH_VALUE

--------------- --------------- ---------- -------- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61329 3 YES TO_DATE(' 2001-08-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61330 4 YES TO_DATE(' 2001-09-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61331 5 YES TO_DATE(' 2001-10-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

SH@dw24>

SH@dw24> -- Change partition interval

SH@dw24> alter table t_part set INTERVAL(NUMTODSINTERVAL(1,'DAY'));

Table altered.

SH@dw24>

SH@dw24> -- Notice that the formerly interval partitions became range partitions (INTERVAL column is NO)

SH@dw24> -- and the high bound of the last partition became the transition point, where the interval partitions start

SH@dw24>

SH@dw24> select table_name, partition_name, partition_position part_pos,interval,high_value from user_tab_partitions where table_name = 'T_PART' order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INTERVAL HIGH_VALUE

--------------- --------------- ---------- -------- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61329 3 NO TO_DATE(' 2001-08-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61330 4 NO TO_DATE(' 2001-09-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61331 5 NO TO_DATE(' 2001-10-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

SH@dw24>

SH@dw24> -- Note that due to the transition point changed the following 3 inserts will not create new day partitions,

SH@dw24> -- rows will go into existing range partitions

SH@dw24> insert into t_part values (TO_DATE('2001-07-07', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> insert into t_part values (TO_DATE('2001-07-08', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> insert into t_part values (TO_DATE('2001-07-11', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> commit;

Commit complete.

SH@dw24>

SH@dw24> select table_name, partition_name, partition_position part_pos,interval,high_value from user_tab_partitions where table_name = 'T_PART' order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INTERVAL HIGH_VALUE

--------------- --------------- ---------- -------- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61329 3 NO TO_DATE(' 2001-08-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61330 4 NO TO_DATE(' 2001-09-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61331 5 NO TO_DATE(' 2001-10-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

SH@dw24>

SH@dw24> -- These rows will create new day partitions because the partition keys inserted are higher than the transition point

SH@dw24> insert into t_part values (TO_DATE('2001-10-01', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> insert into t_part values (TO_DATE('2001-10-02', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SH@dw24> commit;

Commit complete.

SH@dw24>

SH@dw24> select table_name, partition_name, partition_position part_pos,interval,high_value from user_tab_partitions where table_name = 'T_PART' order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INTERVAL HIGH_VALUE

--------------- --------------- ---------- -------- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61329 3 NO TO_DATE(' 2001-08-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61330 4 NO TO_DATE(' 2001-09-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61331 5 NO TO_DATE(' 2001-10-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61332 6 YES TO_DATE(' 2001-10-02 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P61333 7 YES TO_DATE(' 2001-10-03 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

7 rows selected.

How to perform Partition Maintenance Operations (PMOP)?

In pmop operations you have to refer to the partition(s). You can query the *_TAB_PARTITIONS data dictionary view to find out the system-generated partition name, or you can use the FOR syntax to identify a partition that was system-generated (currently FOR syntax works for table only, not for indexes).

Exchanging a Partition of an Interval Partitioned Table

You can exchange interval partitions in an interval-partitioned table. However, you have to make sure the interval partition has been created before you can exchange the partition. You can let the database create the partition by locking the interval partition.

The following example shows a partition exchange for the T_PART table, interval-partitioned using daily partitions. This example shows how to add data for 6th of July 2001 to the table using partition exchange load.

Table PARTITION_NAME HIGH_VALUE

----------------- ------------------------- -------------------------------

T_PART P_200105 TIMESTAMP' 2001-06-01 00:00:00'

T_PART P_200106 TIMESTAMP' 2001-07-01 00:00:00'

T_PART SYS_P5793 TIMESTAMP' 2001-07-03 00:00:00'

T_PART SYS_P5794 TIMESTAMP' 2001-07-04 00:00:00'

T_PART SYS_P5795 TIMESTAMP' 2001-07-02 00:00:00'

T_PART SYS_P5796 TIMESTAMP' 2001-07-05 00:00:00'

-- as can be see in dba_tab_partitions, there is no partition created to accommodate 06-JUL-2001,

-- hence we execute the following command, which creates the corresponding partition

LOCK TABLE t_part

PARTITION FOR (TO_DATE('06-JUL-2001','dd-MON-yyyy'))

IN SHARE MODE;

-- the corresponding partition SYS_P5813 is created

Table PARTITION_NAME HIGH_VALUE

----------------- ------------------------- --------------------------------

T_PART P_200105 TIMESTAMP' 2001-06-01 00:00:00'

T_PART P_200106 TIMESTAMP' 2001-07-01 00:00:00'

T_PART SYS_P5793 TIMESTAMP' 2001-07-03 00:00:00'

T_PART SYS_P5794 TIMESTAMP' 2001-07-04 00:00:00'

T_PART SYS_P5795 TIMESTAMP' 2001-07-02 00:00:00'

T_PART SYS_P5796 TIMESTAMP' 2001-07-05 00:00:00'

T_PART SYS_P5813 TIMESTAMP' 2001-07-07 00:00:00'

-- so you can execute the exchange partition command now

ALTER TABLE interval_sales

EXCHANGE PARTITION FOR (TO_DATE('06-JUL-2001','dd-MON-yyyy'))

WITH TABLE interval_sales_jul_2001

....;

Dropping interval partition

This operation drops the data for the interval only and leaves the interval definition intact. The partition segment is dropped, so it does no longer appear in the dba_tab_partitions view. If data is inserted in the interval just dropped, then the database again creates an interval partition.

ALTER TABLE T_PART DROP PARTITION FOR (TO_DATE('06-JUL-2001','dd-MON-yyyy'));

See also Document 1285036.1 How To Drop The Interval Partitions?

Merging partitions

The contents of two adjacent interval partitions can be merged into one partition. Nonadjacent interval partitions cannot be merged. The first interval partition can also be merged with the highest range partition.

The resulting partition can be a new partition name or the name of the highest partition of the merged ones (otherwise error ORA-14275: cannot reuse lower-bound partition as resulting partition).

Worth noting that merging interval partitions will move the transition point where the interval partitioning starts to the high bound of the resulting partition. All partitions below the transition point became range partitions.

An example can be seen below.

SQL> create table t_part (

2 col_date date,

3 col_number number(10))

4 PARTITION BY RANGE (col_date)

5 interval(numtodsinterval(1,'day'))

6 (

7 PARTITION P_200105 VALUES LESS THAN (TO_DATE('2001-06-01', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN')),

8 PARTITION P_200106 VALUES LESS THAN (TO_DATE('2001-07-01', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'))

9 )

10 ;

Table created.

SQL> insert into t_part values (TO_DATE('2001-07-05', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SQL> insert into t_part values (TO_DATE('2001-07-07', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SQL> insert into t_part values (TO_DATE('2001-07-08', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SQL> insert into t_part values (TO_DATE('2001-07-11', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SQL> commit;

Commit complete.

SQL> select table_name, partition_name, partition_position part_pos

2 ,interval,high_value

3 from user_tab_partitions

4 where table_name = 'T_PART'

5 order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INT HIGH_VALUE

------------------------------ ------------------------------ ---------- --- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22469 3 YES TO_DATE(' 2001-07-06 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22470 4 YES TO_DATE(' 2001-07-08 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22471 5 YES TO_DATE(' 2001-07-09 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22472 6 YES TO_DATE(' 2001-07-12 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

6 rows selected.

The interval partitioning starts from the high bound of the highest range partition P_200106, and due to the inserts 4 interval partitions are created named SYS_P%.

Not that SYS_P22469 and SYS_P22470 partitions though look adjecent according to the current physical structure of the partitions, but considering the 1 DAY interval partitioning that is currently applied for the table,

these partitions are not adjecent, hence the merge of these partitions are expected to fails as it can be seen below:

SQL> alter table t_part merge partitions SYS_P22469, SYS_P22470 into partition MyFav;

alter table t_part merge partitions SYS_P22469, SYS_P22470 into partition MyFav

ERROR at line 1:

ORA-14274: partitions being merged are not adjacent

SQL> alter table t_part merge partitions for (TO_DATE('2001-07-05', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN')),

2 for (TO_DATE('2001-07-07', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN')) into partition MyFav;

alter table t_part merge partitions for (TO_DATE('2001-07-05', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN')),

ERROR at line 1:

ORA-14274: partitions being merged are not adjacent

Interval partitions SYS_P22470 and SYS_P22471 are adjecent even according to the interval partitioning clause applied on the table, hence these can be merged.

SQL> alter table t_part merge partitions SYS_P22470,SYS_P22471 into partition MyFav;

Table altered.

SQL> select table_name, partition_name, partition_position part_pos

2 ,interval,high_value

3 from user_tab_partitions

4 where table_name = 'T_PART'

5 order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INT HIGH_VALUE

------------------------------ ------------------------------ ---------- --- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22469 3 NO TO_DATE(' 2001-07-06 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART MYFAV 4 NO TO_DATE(' 2001-07-09 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22472 5 YES TO_DATE(' 2001-07-12 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

Note however that by merging 2 interval partitions the transition point, where the interval partitioning starts, now moved to the high bound of the resulting partition MYFAV. All partitions below the transition point (including partition MYFAV) became range partitions, as this can be verified below.

SQL> insert into t_part values (TO_DATE('2001-07-04', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SQL> commit;

Commit complete.

SQL> select table_name, partition_name, partition_position part_pos

2 ,interval,high_value

3 from user_tab_partitions

4 where table_name = 'T_PART'

5 order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INT HIGH_VALUE

------------------------------ ------------------------------ ---------- --- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22469 3 NO TO_DATE(' 2001-07-06 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART MYFAV 4 NO TO_DATE(' 2001-07-09 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22472 6 YES TO_DATE(' 2001-07-12 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

SQL> insert into t_part values (TO_DATE('2001-07-10', 'YYYY-MM-DD', 'NLS_CALENDAR=GREGORIAN'),1);

1 row created.

SQL> commit;

Commit complete.

SQL> select table_name, partition_name, partition_position part_pos

2 ,interval,high_value

3 from user_tab_partitions

4 where table_name = 'T_PART'

5 order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INT HIGH_VALUE

------------------------------ ------------------------------ ---------- --- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22469 3 NO TO_DATE(' 2001-07-06 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART MYFAV 4 NO TO_DATE(' 2001-07-09 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22473 5 YES TO_DATE(' 2001-07-11 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22472 6 YES TO_DATE(' 2001-07-12 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

6 rows selected.

Splitting interval partition

When you split an interval partition, the operation will also move the transition point to the upper-most endpoint of the new partition created from the split.

In the following example let's use table t_part from the previous section where the table is partitioned by interval 1 DAY.

Partition SYS_P22473 has its high bound 2001-07-11 00:00:00, so it is supposed to contain rows for 2001-07-10.

We split interval partition SYS_P22473 into a partition called MORNING and into the original partition SYS_P22473.

SQL> select table_name, partition_name, partition_position part_pos

2 ,interval,high_value

3 from user_tab_partitions

4 where table_name = 'T_PART'

5 order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INT HIGH_VALUE

------------------------------ ------------------------------ ---------- --- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22469 3 NO TO_DATE(' 2001-07-06 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART MYFAV 4 NO TO_DATE(' 2001-07-09 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22473 5 YES TO_DATE(' 2001-07-11 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22472 6 YES TO_DATE(' 2001-07-12 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

6 rows selected.

SQL> alter table t_part split partition SYS_P22473 at (TO_DATE(' 2001-07-10 12:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIAN'))

2 into (partition morning, partition SYS_P22473);

Table altered.

SQL> select table_name, partition_name, partition_position part_pos

2 ,interval,high_value

3 from user_tab_partitions

4 where table_name = 'T_PART'

5 order by table_name, partition_position;

TABLE_NAME PARTITION_NAME PART_POS INT HIGH_VALUE

------------------------------ ------------------------------ ---------- --- --------------------------------------------------------------------------------

T_PART P_200105 1 NO TO_DATE(' 2001-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART P_200106 2 NO TO_DATE(' 2001-07-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22469 3 NO TO_DATE(' 2001-07-06 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART MYFAV 4 NO TO_DATE(' 2001-07-09 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART MORNING 5 NO TO_DATE(' 2001-07-10 12:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22473 6 NO TO_DATE(' 2001-07-11 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

T_PART SYS_P22472 7 YES TO_DATE(' 2001-07-12 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIA

7 rows selected.

The transition point where the interval partitions start moved to the high bound of partition SYS_P22473.

Renaming interval partition

You can rename interval partition name e.g. rename system generated partition name

Table PARTITION_NAME HIGH_VALUE

----------------- ------------------------- -------------------------------

...

T_PART SYS_P5793 TIMESTAMP' 2001-07-03 00:00:00'

T_PART SYS_P5794 TIMESTAMP' 2001-07-04 00:00:00'

SQL> ALTER TABLE T_PART rename partition SYS_P5793 to p2001_07_02;

Table altered.

Table PARTITION_NAME HIGH_VALUE

----------------- ------------------------- -------------------------------

...

T_PART P2001_07_02 TIMESTAMP' 2001-07-03 00:00:00'

T_PART SYS_P5794 TIMESTAMP' 2001-07-04 00:00:00'

...

How to disable / turn off interval partitioning for a table?

You can disable interval partitioning with the following statement:

ALTER TABLE <table name> SET INTERVAL ();

This makes the table range partitioned with the existing partitions as ranged ones.

Please note turning off and then on interval partitioning will move the transition point where the interval partitions will start to the high bound of the highest existing partition. This is because turning interval partitioning off makes the interval partitions range, and then turning interval partition on will use the high bound of the highest range partition as the transition point.

Partition Count/Pruning

Note that the maximum number of partitions in a table is 1024K -1 = 1048575. With a particular interval set the physical interval partition is created when data comes for that partition, but the database reserves the interval partitions in between physically created partitions as well as upto the maximum number of partitions, since future values can go into any of these partitions.

Consider the following example.

CREATE TABLE t_num

(col1 number)

PARTITION BY RANGE (col1)

INTERVAL(1)

(

PARTITION p1 values less than (1)

);

insert into t_num values (1);

insert into t_num values (2);

insert into t_num values (100);

At this point dba_tab_partitions shows 4 partitions, 3 of those were created due to the 3 above inserts, 1 partition is the initial range partition created at create table time:

Table PARTITION_NAME HIGH_VALUE

----------------- ------------------------- -----------

T_NUM P1 1

T_NUM SYS_P5913 2

T_NUM SYS_P5914 3

T_NUM SYS_P5915 101

The value of the column PARTITION_COUNT in ALL|DBA|USER_part_table shows the theoretical max number of partitions:

TABLE_NAME PARTITION_COUNT

-------------------- ---------------

T_NUM 1048575

If you look into the execution plan of a query that cannot do partition pruning, you see PSTOP=<theoretical max number of partitions>:

SQL> set autotrace on

SQL> select * from t_num;

COL1

----------

100

Execution Plan

----------------------------------------------------------

Plan hash value: 122616543

---------------------------------------------------------------------------------------------

---------------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 7 | 91 | 35 (0)| 00:00:01 | | |

| 1 | PARTITION RANGE ALL| | 7 | 91 | 35 (0)| 00:00:01 | 1 |1048575|

| 2 | TABLE ACCESS FULL | T_NUM | 7 | 91 | 35 (0)| 00:00:01 | 1 |1048575|

---------------------------------------------------------------------------------------------

Now insert value 1048574 into the T_NUM table, this creates a partition with the high value 1048575.

SQL> insert into t_num values (1048574);

1 row created.

Table PARTITION_NAME HIGH_VALUE

----------------- ------------------------- ----------

T_NUM P1 1

T_NUM SYS_P5913 2

T_NUM SYS_P5914 3

T_NUM SYS_P5915 101

T_NUM SYS_P5916 1048575

dba_tab_partitions shows only 5 physically created partitions as 4 rows are in the table, but due to interval(1) is set for the table, we cannot insert a larger value e.g. 1048575, because the corresponding partition would need to have high value 1048576, and this would exceed the theoretical number of partitions for the table:

insert into t_num values (1048575)

ERROR at line 1:

ORA-14300: partitioning key maps to a partition outside maximum permitted number of partitions

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