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Filtered Partition Maintenance Operations in Oracle Database 12c Release 2 (12.2)

Oracle Database 12c Release 2 (12.2) allows you to add a filter condition when you move, split or merge a partition, move a table or convert a non-partitioned table to a partitioned table. Only those rows matching the filter condition are included in the resulting object.

Filtered Split Partition

The filter condition is only allowed on heap tables, can only reference columns from the table and can be used in conjunction with online operations with some additional considerations.

This article provides some simple examples using filter conditions with maintenance operations. The examples in this article are mostly based on partition management operations, but this functionality applies equally to subpartition maintenance operations.

Related articles.

Move a Table

Create and populate a new test table.

DROP TABLE t1 PURGE;

CREATE TABLE t1 AS
SELECT level AS id,
       'Description for ' || level AS description
FROM   dual
CONNECT BY level <= 100;
COMMIT;

Check the contents of the table.

SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
       100          1        100

SQL>

Move the table, filtering out rows with an ID value greater than 50.

ALTER TABLE t1 MOVE ONLINE
  INCLUDING ROWS WHERE id <= 50;

Check the contents of the table.

SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
        50          1         50

SQL>

The rows with an ID value between 51 and 100 have been removed.

Convert a Non-Partitioned Table to a Partitioned Table

Create and populate a new test table.

DROP TABLE t1 PURGE;

CREATE TABLE t1 AS
SELECT level AS id,
       'Description for ' || level AS description
FROM   dual
CONNECT BY level <= 100;
COMMIT;

Check the contents of the table.

SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
       100          1        100

SQL>

Convert the table to a partitioned, filtering out rows with an ID value greater than 50.

ALTER TABLE t1 MODIFY
  PARTITION BY RANGE (id) (
    PARTITION t1_le_50 VALUES LESS THAN (51),
    PARTITION t1_le_101 VALUES LESS THAN (101)
  )
  INCLUDING ROWS WHERE id <= 50;

Check the contents of the partitions.

EXEC DBMS_STATS.gather_table_stats(USER, 'T1');

COLUMN table_name FORMAT A20
COLUMN partition_name FORMAT A20
COLUMN high_value FORMAT A20

SELECT table_name, partition_name, high_value, num_rows
FROM   user_tab_partitions
WHERE  table_name = 'T1'
ORDER BY 1,2;

TABLE_NAME           PARTITION_NAME       HIGH_VALUE             NUM_ROWS
-------------------- -------------------- -------------------- ----------
T1                   T1_LE_101            101                           0
T1                   T1_LE_50             51                           50

SQL>


SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
        50          1         50

SQL>

The rows with an ID value between 51 and 100 have been removed.

Move a Partition

Create and populate a new test partitioned table.

DROP TABLE t1 PURGE;

CREATE TABLE t1 (
  id            NUMBER,
  description   VARCHAR2(50)
)
PARTITION BY RANGE (id)
(
  PARTITION t1_le_50 VALUES LESS THAN (51),
  PARTITION t1_le_101 VALUES LESS THAN (101)
);

INSERT INTO t1
SELECT level AS id,
       'Description for ' || level AS description
FROM   dual
CONNECT BY level <= 100;
COMMIT;

Check the contents of the partitions.

EXEC DBMS_STATS.gather_table_stats(USER, 'T1');

COLUMN table_name FORMAT A20
COLUMN partition_name FORMAT A20
COLUMN high_value FORMAT A20

SELECT table_name, partition_name, high_value, num_rows
FROM   user_tab_partitions
WHERE  table_name = 'T1'
ORDER BY 1,2;

TABLE_NAME           PARTITION_NAME       HIGH_VALUE             NUM_ROWS
-------------------- -------------------- -------------------- ----------
T1                   T1_LE_101            101                          50
T1                   T1_LE_50             51                           50

SQL>


SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
       100          1        100

SQL>

Move a partition, filtering out rows with an ID value greater than 50.

ALTER TABLE t1 MOVE PARTITION t1_le_101 ONLINE TABLESPACE users
  INCLUDING ROWS WHERE id <= 50;

Check the contents of the partitions.

EXEC DBMS_STATS.gather_table_stats(USER, 'T1');

COLUMN table_name FORMAT A20
COLUMN partition_name FORMAT A20
COLUMN high_value FORMAT A20

SELECT table_name, partition_name, high_value, num_rows
FROM   user_tab_partitions
WHERE  table_name = 'T1'
ORDER BY 1,2;

TABLE_NAME           PARTITION_NAME       HIGH_VALUE             NUM_ROWS
-------------------- -------------------- -------------------- ----------
T1                   T1_LE_101            101                           0
T1                   T1_LE_50             51                           50

SQL>


SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
        50          1         50

SQL>

The rows with an ID value between 51 and 100 have been removed.

Split a Partition

Create and populate a new test partitioned table.

DROP TABLE t1 PURGE;

CREATE TABLE t1 (
  id            NUMBER,
  description   VARCHAR2(50)
)
PARTITION BY RANGE (id)
(
  PARTITION t1_le_101 VALUES LESS THAN (101)
);

INSERT INTO t1
SELECT level AS id,
       'Description for ' || level AS description
FROM   dual
CONNECT BY level <= 100;
COMMIT;

Check the contents of the partition.

EXEC DBMS_STATS.gather_table_stats(USER, 'T1');

COLUMN table_name FORMAT A20
COLUMN partition_name FORMAT A20
COLUMN high_value FORMAT A20

SELECT table_name, partition_name, high_value, num_rows
FROM   user_tab_partitions
WHERE  table_name = 'T1'
ORDER BY 1,2;

TABLE_NAME           PARTITION_NAME       HIGH_VALUE             NUM_ROWS
-------------------- -------------------- -------------------- ----------
T1                   T1_LE_101            101                         100

SQL>


SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
       100          1        100

SQL>

Split the partition, filtering out rows with an ID value greater than 50.

ALTER TABLE t1
  SPLIT PARTITION t1_le_101 AT (51)
  INTO (PARTITION t1_le_51,
        PARTITION t1_le_101)
  INCLUDING ROWS WHERE id <= 50
  ONLINE;

Check the contents of the partitions.

EXEC DBMS_STATS.gather_table_stats(USER, 'T1');

COLUMN table_name FORMAT A20
COLUMN partition_name FORMAT A20
COLUMN high_value FORMAT A20

SELECT table_name, partition_name, high_value, num_rows
FROM   user_tab_partitions
WHERE  table_name = 'T1'
ORDER BY 1,2;

TABLE_NAME           PARTITION_NAME       HIGH_VALUE             NUM_ROWS
-------------------- -------------------- -------------------- ----------
T1                   T1_LE_101            101                           0
T1                   T1_LE_51             51                           50

SQL>


SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
        50          1         50

SQL>

The rows with an ID value between 51 and 100 have been removed.

Merge Partitions

Create and populate a new test partitioned table.

DROP TABLE t1 PURGE;

CREATE TABLE t1 (
  id            NUMBER,
  description   VARCHAR2(50)
)
PARTITION BY RANGE (id)
(
  PARTITION t1_le_51 VALUES LESS THAN (51),
  PARTITION t1_le_101 VALUES LESS THAN (101)
);

INSERT INTO t1
SELECT level AS id,
       'Description for ' || level AS description
FROM   dual
CONNECT BY level <= 100;
COMMIT;

Check the contents of the partitions.

EXEC DBMS_STATS.gather_table_stats(USER, 'T1');

COLUMN table_name FORMAT A20
COLUMN partition_name FORMAT A20
COLUMN high_value FORMAT A20

SELECT table_name, partition_name, high_value, num_rows
FROM   user_tab_partitions
WHERE  table_name = 'T1'
ORDER BY 1,2;

TABLE_NAME           PARTITION_NAME       HIGH_VALUE             NUM_ROWS
-------------------- -------------------- -------------------- ----------
T1                   T1_LE_101            101                          50
T1                   T1_LE_51             51                           50

SQL>


SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
       100          1        100

SQL>

Merge the partitions, filtering out rows with an ID value greater than 50.

ALTER TABLE t1
  MERGE PARTITIONS t1_le_51, t1_le_101
  INTO PARTITION t1_le_101
  INCLUDING ROWS WHERE id <= 50;

Check the contents of the partitions.

EXEC DBMS_STATS.gather_table_stats(USER, 'T1');

COLUMN table_name FORMAT A20
COLUMN partition_name FORMAT A20
COLUMN high_value FORMAT A20

SELECT table_name, partition_name, high_value, num_rows
FROM   user_tab_partitions
WHERE  table_name = 'T1'
ORDER BY 1,2;

TABLE_NAME           PARTITION_NAME       HIGH_VALUE             NUM_ROWS
-------------------- -------------------- -------------------- ----------
T1                   T1_LE_101            101                          50

SQL>


SELECT COUNT(*) AS total_rows,
       MIN(id) AS min_id,
       MAX(id) AS max_id
FROM   t1;

TOTAL_ROWS     MIN_ID     MAX_ID
---------- ---------- ----------
        50          1         50

SQL>

The rows with an ID value between 51 and 100 have been removed.

For more information see:

Hope this helps. Regards Tim...

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