Creating Partitions

Creating Range-Partitioned Tables and Global Indexes

The PARTITION BY RANGE clause of the CREATE TABLE statement specifies that the table or index is to be range-partitioned. The PARTITION clauses identify the individual partition ranges, and the optional subclauses of a PARTITION clause can specify physical and other attributes specific to a partition segment. If not overridden at the partition level, partitions inherit the attributes of their underlying table.

CREATE TABLE sales
  ( prod_id       NUMBER(6)
  , cust_id       NUMBER
  , time_id       DATE
  , channel_id    CHAR(1)
  , promo_id      NUMBER(6)
  , quantity_sold NUMBER(3)
  , amount_sold   NUMBER(10,2)
  )
 PARTITION BY RANGE (time_id)
 ( PARTITION sales_q1_2006 VALUES LESS THAN (TO_DATE('01-APR-2006','dd-MON-yyyy'))
    TABLESPACE tsa
 , PARTITION sales_q2_2006 VALUES LESS THAN (TO_DATE('01-JUL-2006','dd-MON-yyyy'))
    TABLESPACE tsb
 , PARTITION sales_q3_2006 VALUES LESS THAN (TO_DATE('01-OCT-2006','dd-MON-yyyy'))
    TABLESPACE tsc
 , PARTITION sales_q4_2006 VALUES LESS THAN (TO_DATE('01-JAN-2007','dd-MON-yyyy'))
    TABLESPACE tsd
 );

CREATE TABLE sales
  ( prod_id       NUMBER(6)
  , cust_id       NUMBER
  , time_id       DATE
  , channel_id    CHAR(1)
  , promo_id      NUMBER(6)
  , quantity_sold NUMBER(3)
  , amount_sold   NUMBER(10,2)
  )
 STORAGE (INITIAL 100K NEXT 50K) LOGGING
 PARTITION BY RANGE (time_id)
 ( PARTITION sales_q1_2006 VALUES LESS THAN (TO_DATE('01-APR-2006','dd-MON-yyyy'))
    TABLESPACE tsa STORAGE (INITIAL 20K NEXT 10K)
 , PARTITION sales_q2_2006 VALUES LESS THAN (TO_DATE('01-JUL-2006','dd-MON-yyyy'))
    TABLESPACE tsb
 , PARTITION sales_q3_2006 VALUES LESS THAN (TO_DATE('01-OCT-2006','dd-MON-yyyy'))
    TABLESPACE tsc
 , PARTITION sales_q4_2006 VALUES LESS THAN (TO_DATE('01-JAN-2007','dd-MON-yyyy'))
    TABLESPACE tsd
 )
 ENABLE ROW MOVEMENT;

CREATE INDEX amount_sold_ix ON sales(amount_sold)
   GLOBAL PARTITION BY RANGE(sale_month)
      ( PARTITION p_100 VALUES LESS THAN (100)
      , PARTITION p_1000 VALUES LESS THAN (1000)
      , PARTITION p_10000 VALUES LESS THAN (10000)
      , PARTITION p_100000 VALUES LESS THAN (100000)
      , PARTITION p_1000000 VALUES LESS THAN (1000000)
      , PARTITION p_greater_than_1000000 VALUES LESS THAN (maxvalue)
      );

Creating Interval-Partitioned Tables

The INTERVAL clause of the CREATE TABLE statement establishes interval partitioning for the table. You must specify at least one range partition using the PARTITION clause. The range partitioning key value determines the high value of the range partitions, which is called the transition point, and the database automatically creates interval partitions for data beyond that transition point. The lower boundary of every interval partition is the non-inclusive upper boundary of the previous range or interval partition.

For example, if you create an interval partitioned table with monthly intervals and the transition point is at January 1, 2010, then the lower boundary for the January 2010 interval is January 1, 2010. The lower boundary for the July 2010 interval is July 1, 2010, regardless of whether the June 2010 partition was previously created. Note, however, that using a date where the high or low bound of the partition would be out of the range set for storage causes an error. For example, TO_DATE('9999-12-01', 'YYYY-MM-DD') causes the high bound to be 10000-01-01, which would not be storable if 10000 is out of the legal range.

For interval partitioning, the partitioning key can only be a single column name from the table and it must be of NUMBER or DATE type. The optional STORE IN clause lets you specify one or more tablespaces into which the database stores interval partition data using a round-robin algorithm for subsequently created interval partitions.

Example 4-4 specifies four partitions with varying interval widths. It also specifies that above the transition point of January 1, 2010, partitions are created with an interval width of one month.

CREATE TABLE interval_sales
    ( prod_id        NUMBER(6)
    , cust_id        NUMBER
    , time_id        DATE
    , channel_id     CHAR(1)
    , promo_id       NUMBER(6)
    , quantity_sold  NUMBER(3)
    , amount_sold    NUMBER(10,2)
    ) 
  PARTITION BY RANGE (time_id) 
  INTERVAL(NUMTOYMINTERVAL(1, 'MONTH'))
    ( PARTITION p0 VALUES LESS THAN (TO_DATE('1-1-2008', 'DD-MM-YYYY')),
      PARTITION p1 VALUES LESS THAN (TO_DATE('1-1-2009', 'DD-MM-YYYY')),
      PARTITION p2 VALUES LESS THAN (TO_DATE('1-7-2009', 'DD-MM-YYYY')),
      PARTITION p3 VALUES LESS THAN (TO_DATE('1-1-2010', 'DD-MM-YYYY')) );

The high bound of partition p3 represents the transition point. p3 and all partitions below it (p0, p1, and p2 in this example) are in the range section while all partitions above it fall into the interval section.

Creating Hash-Partitioned Tables and Global Indexes

The PARTITION BY HASH clause of the CREATE TABLE statement identifies that the table is to be hash-partitioned. The PARTITIONS clause can then be used to specify the number of partitions to create, and optionally, the tablespaces to store them in. Alternatively, you can use PARTITION clauses to name the individual partitions and their tablespaces.

The only attribute you can specify for hash partitions is TABLESPACE. All of the hash partitions of a table must share the same segment attributes (except TABLESPACE), which are inherited from the table level.

CREATE TABLE scubagear
     (id NUMBER,
      name VARCHAR2 (60))
   PARTITION BY HASH (id)
   PARTITIONS 4 
   STORE IN (gear1, gear2, gear3, gear4);

CREATE TABLE dept (deptno NUMBER, deptname VARCHAR(32))
     PARTITION BY HASH(deptno) PARTITIONS 16;

CREATE TABLE dept (deptno NUMBER, deptname VARCHAR(32))
     STORAGE (INITIAL 10K)
     PARTITION BY HASH(deptno)
       (PARTITION p1 TABLESPACE ts1, PARTITION p2 TABLESPACE ts2,
        PARTITION p3 TABLESPACE ts1, PARTITION p4 TABLESPACE ts3);

CREATE INDEX loc_dept_ix ON dept(deptno) LOCAL;

CREATE INDEX hgidx ON tab (c1,c2,c3) GLOBAL
     PARTITION BY HASH (c1,c2)
     (PARTITION p1  TABLESPACE tbs_1,
      PARTITION p2  TABLESPACE tbs_2,
      PARTITION p3  TABLESPACE tbs_3,
      PARTITION p4  TABLESPACE tbs_4);

Creating List-Partitioned Tables

The semantics for creating list partitions are very similar to those for creating range partitions. However, to create list partitions, you specify a PARTITION BY LIST clause in the CREATE TABLE statement, and the PARTITION clauses specify lists of literal values, which are the discrete values of the partitioning columns that qualify rows to be included in the partition. For list partitioning, the partitioning key can only be a single column name from the table.

Available only with list partitioning, you can use the keyword DEFAULT to describe the value list for a partition. This identifies a partition that accommodates rows that do not map into any of the other partitions.

As with range partitions, optional subclauses of a PARTITION clause can specify physical and other attributes specific to a partition segment. If not overridden at the partition level, partitions inherit the attributes of their parent table.

Example 4-7 creates a list-partitioned table. It creates table q1_sales_by_region which is partitioned by regions consisting of groups of U.S. states.

CREATE TABLE q1_sales_by_region
      (deptno number, 
       deptname varchar2(20),
       quarterly_sales number(10, 2),
       state varchar2(2))
   PARTITION BY LIST (state)
      (PARTITION q1_northwest VALUES ('OR', 'WA'),
       PARTITION q1_southwest VALUES ('AZ', 'UT', 'NM'),
       PARTITION q1_northeast VALUES  ('NY', 'VM', 'NJ'),
       PARTITION q1_southeast VALUES ('FL', 'GA'),
       PARTITION q1_northcentral VALUES ('SD', 'WI'),
       PARTITION q1_southcentral VALUES ('OK', 'TX'));

A row is mapped to a partition by checking whether the value of the partitioning column for a row matches a value in the value list that describes the partition.

For example, some sample rows are inserted as follows:

• (10, 'accounting', 100, 'WA') maps to partition q1_northwest

• (20, 'R&D', 150, 'OR') maps to partition q1_northwest

• (30, 'sales', 100, 'FL') maps to partition q1_southeast

• (40, 'HR', 10, 'TX') maps to partition q1_southwest

• (50, 'systems engineering', 10, 'CA') does not map to any partition in the table and raises an error

Unlike range partitioning, with list partitioning, there is no apparent sense of order between partitions. You can also specify a default partition into which rows that do not map to any other partition are mapped. If a default partition were specified in the preceding example, the state CA would map to that partition.

Example 4-8 creates table sales_by_region and partitions it using the list method. The first two PARTITION clauses specify physical attributes, which override the table-level defaults. The remaining PARTITION clauses do not specify attributes and those partitions inherit their physical attributes from table-level defaults. A default partition is also specified.

CREATE TABLE sales_by_region (item# INTEGER, qty INTEGER, 
             store_name VARCHAR(30), state_code VARCHAR(2),
             sale_date DATE)
     STORAGE(INITIAL 10K NEXT 20K) TABLESPACE tbs5 
     PARTITION BY LIST (state_code) 
     (
     PARTITION region_east
        VALUES ('MA','NY','CT','NH','ME','MD','VA','PA','NJ')
        STORAGE (INITIAL 8M) 
        TABLESPACE tbs8,
     PARTITION region_west
        VALUES ('CA','AZ','NM','OR','WA','UT','NV','CO')
        NOLOGGING,
     PARTITION region_south
        VALUES ('TX','KY','TN','LA','MS','AR','AL','GA'),
     PARTITION region_central 
        VALUES ('OH','ND','SD','MO','IL','MI','IA'),
     PARTITION region_null
        VALUES (NULL),
     PARTITION region_unknown
        VALUES (DEFAULT)
     );

Creating Reference-Partitioned Tables

To create a reference-partitioned table, you specify a PARTITION BY REFERENCE clause in the CREATE TABLE statement. This clause specifies the name of a referential constraint and this constraint becomes the partitioning referential constraint that is used as the basis for reference partitioning in the table. The referential constraint must be enabled and enforced.

As with other partitioned tables, you can specify object-level default attributes, and you can optionally specify partition descriptors that override the object-level defaults on a per-partition basis.

Example 4-9 creates a parent table orders which is range-partitioned on order_date. The reference-partitioned child table order_items is created with four partitions, Q1_2005, Q2_2005, Q3_2005, and Q4_2005, where each partition contains the order_items rows corresponding to orders in the respective parent partition.

CREATE TABLE orders
    ( order_id           NUMBER(12),
      order_date         TIMESTAMP WITH LOCAL TIME ZONE,
      order_mode         VARCHAR2(8),
      customer_id        NUMBER(6),
      order_status       NUMBER(2),
      order_total        NUMBER(8,2),
      sales_rep_id       NUMBER(6),
      promotion_id       NUMBER(6),
      CONSTRAINT orders_pk PRIMARY KEY(order_id)
    )
  PARTITION BY RANGE(order_date)
    ( PARTITION Q1_2005 VALUES LESS THAN (TO_DATE('01-APR-2005','DD-MON-YYYY')),
      PARTITION Q2_2005 VALUES LESS THAN (TO_DATE('01-JUL-2005','DD-MON-YYYY')),
      PARTITION Q3_2005 VALUES LESS THAN (TO_DATE('01-OCT-2005','DD-MON-YYYY')),
      PARTITION Q4_2005 VALUES LESS THAN (TO_DATE('01-JAN-2006','DD-MON-YYYY'))
    );

CREATE TABLE order_items
    ( order_id           NUMBER(12) NOT NULL,
      line_item_id       NUMBER(3)  NOT NULL,
      product_id         NUMBER(6)  NOT NULL,
      unit_price         NUMBER(8,2),
      quantity           NUMBER(8),
      CONSTRAINT order_items_fk
      FOREIGN KEY(order_id) REFERENCES orders(order_id)
    )
    PARTITION BY REFERENCE(order_items_fk);

If partition descriptors are provided, then the number of partitions described must exactly equal the number of partitions or subpartitions in the referenced table. If the parent table is a composite partitioned table, then the table has one partition for each subpartition of its parent; otherwise the table has one partition for each partition of its parent.

Partition bounds cannot be specified for the partitions of a reference-partitioned table.

The partitions of a reference-partitioned table can be named. If a partition is not explicitly named, then it inherits its name from the corresponding partition in the parent table, unless this inherited name conflicts with an existing explicit name. In this case, the partition has a system-generated name.

Partitions of a reference-partitioned table collocate with the corresponding partition of the parent table, if no explicit tablespace is specified for the reference-partitioned table's partition.

Creating Composite Partitioned Tables

To create a composite partitioned table, you start by using the PARTITION BY [RANGE | LIST] clause of a CREATE TABLE statement. Next, you specify a SUBPARTITION BY [RANGE | LIST | HASH] clause that follows similar syntax and rules as the PARTITION BY [RANGE | LIST | HASH] clause. The individual PARTITION and SUBPARTITION or SUBPARTITIONS clauses, and optionally a SUBPARTITION TEMPLATE clause, follow.

CREATE TABLE sales
  ( prod_id       NUMBER(6)
  , cust_id       NUMBER
  , time_id       DATE
  , channel_id    CHAR(1)
  , promo_id      NUMBER(6)
  , quantity_sold NUMBER(3)
  , amount_sold   NUMBER(10,2)
  )
 PARTITION BY RANGE (time_id) SUBPARTITION BY HASH (cust_id)
  SUBPARTITIONS 8 STORE IN (ts1, ts2, ts3, ts4)
 ( PARTITION sales_q1_2006 VALUES LESS THAN (TO_DATE('01-APR-2006','dd-MON-yyyy'))
 , PARTITION sales_q2_2006 VALUES LESS THAN (TO_DATE('01-JUL-2006','dd-MON-yyyy'))
 , PARTITION sales_q3_2006 VALUES LESS THAN (TO_DATE('01-OCT-2006','dd-MON-yyyy'))
 , PARTITION sales_q4_2006 VALUES LESS THAN (TO_DATE('01-JAN-2007','dd-MON-yyyy'))
 );

CREATE TABLE emp (deptno NUMBER, empname VARCHAR(32), grade NUMBER)   
     PARTITION BY RANGE(deptno) SUBPARTITION BY HASH(empname)
        SUBPARTITIONS 8 STORE IN (ts1, ts3, ts5, ts7)
    (PARTITION p1 VALUES LESS THAN (1000),
     PARTITION p2 VALUES LESS THAN (2000)
        STORE IN (ts2, ts4, ts6, ts8),
     PARTITION p3 VALUES LESS THAN (MAXVALUE)
       (SUBPARTITION p3_s1 TABLESPACE ts4,
        SUBPARTITION p3_s2 TABLESPACE ts5));

CREATE INDEX emp_ix ON emp(deptno)
     LOCAL STORE IN (ts7, ts8, ts9);

CREATE TABLE quarterly_regional_sales
      (deptno number, item_no varchar2(20),
       txn_date date, txn_amount number, state varchar2(2))
  TABLESPACE ts4
  PARTITION BY RANGE (txn_date)
    SUBPARTITION BY LIST (state)
      (PARTITION q1_1999 VALUES LESS THAN (TO_DATE('1-APR-1999','DD-MON-YYYY'))
         (SUBPARTITION q1_1999_northwest VALUES ('OR', 'WA'),
          SUBPARTITION q1_1999_southwest VALUES ('AZ', 'UT', 'NM'),
          SUBPARTITION q1_1999_northeast VALUES ('NY', 'VM', 'NJ'),
          SUBPARTITION q1_1999_southeast VALUES ('FL', 'GA'),
          SUBPARTITION q1_1999_northcentral VALUES ('SD', 'WI'),
          SUBPARTITION q1_1999_southcentral VALUES ('OK', 'TX')
         ),
       PARTITION q2_1999 VALUES LESS THAN ( TO_DATE('1-JUL-1999','DD-MON-YYYY'))
         (SUBPARTITION q2_1999_northwest VALUES ('OR', 'WA'),
          SUBPARTITION q2_1999_southwest VALUES ('AZ', 'UT', 'NM'),
          SUBPARTITION q2_1999_northeast VALUES ('NY', 'VM', 'NJ'),
          SUBPARTITION q2_1999_southeast VALUES ('FL', 'GA'),
          SUBPARTITION q2_1999_northcentral VALUES ('SD', 'WI'),
          SUBPARTITION q2_1999_southcentral VALUES ('OK', 'TX')
         ),
       PARTITION q3_1999 VALUES LESS THAN (TO_DATE('1-OCT-1999','DD-MON-YYYY'))
         (SUBPARTITION q3_1999_northwest VALUES ('OR', 'WA'),
          SUBPARTITION q3_1999_southwest VALUES ('AZ', 'UT', 'NM'),
          SUBPARTITION q3_1999_northeast VALUES ('NY', 'VM', 'NJ'),
          SUBPARTITION q3_1999_southeast VALUES ('FL', 'GA'),
          SUBPARTITION q3_1999_northcentral VALUES ('SD', 'WI'),
          SUBPARTITION q3_1999_southcentral VALUES ('OK', 'TX')
         ),
       PARTITION q4_1999 VALUES LESS THAN ( TO_DATE('1-JAN-2000','DD-MON-YYYY'))
         (SUBPARTITION q4_1999_northwest VALUES ('OR', 'WA'),
          SUBPARTITION q4_1999_southwest VALUES ('AZ', 'UT', 'NM'),
          SUBPARTITION q4_1999_northeast VALUES ('NY', 'VM', 'NJ'),
          SUBPARTITION q4_1999_southeast VALUES ('FL', 'GA'),
          SUBPARTITION q4_1999_northcentral VALUES ('SD', 'WI'),
          SUBPARTITION q4_1999_southcentral VALUES ('OK', 'TX')
         )
      );

CREATE TABLE sample_regional_sales
      (deptno number, item_no varchar2(20),
       txn_date date, txn_amount number, state varchar2(2))
  PARTITION BY RANGE (txn_date)
    SUBPARTITION BY LIST (state)
      (PARTITION q1_1999 VALUES LESS THAN (TO_DATE('1-APR-1999','DD-MON-YYYY'))
          TABLESPACE tbs_1
         (SUBPARTITION q1_1999_northwest VALUES ('OR', 'WA'),
          SUBPARTITION q1_1999_southwest VALUES ('AZ', 'UT', 'NM'),
          SUBPARTITION q1_1999_northeast VALUES ('NY', 'VM', 'NJ'),
          SUBPARTITION q1_1999_southeast VALUES ('FL', 'GA'),
          SUBPARTITION q1_others VALUES (DEFAULT) TABLESPACE tbs_4
         ),
       PARTITION q2_1999 VALUES LESS THAN ( TO_DATE('1-JUL-1999','DD-MON-YYYY'))
          TABLESPACE tbs_2
         (SUBPARTITION q2_1999_northwest VALUES ('OR', 'WA'),
          SUBPARTITION q2_1999_southwest VALUES ('AZ', 'UT', 'NM'),
          SUBPARTITION q2_1999_northeast VALUES ('NY', 'VM', 'NJ'),
          SUBPARTITION q2_1999_southeast VALUES ('FL', 'GA'),
          SUBPARTITION q2_1999_northcentral VALUES ('SD', 'WI'),
          SUBPARTITION q2_1999_southcentral VALUES ('OK', 'TX')
         ),
       PARTITION q3_1999 VALUES LESS THAN (TO_DATE('1-OCT-1999','DD-MON-YYYY'))
          TABLESPACE tbs_3
         (SUBPARTITION q3_1999_northwest VALUES ('OR', 'WA'),
          SUBPARTITION q3_1999_southwest VALUES ('AZ', 'UT', 'NM'),
          SUBPARTITION q3_others VALUES (DEFAULT) TABLESPACE tbs_4
         ),
       PARTITION q4_1999 VALUES LESS THAN ( TO_DATE('1-JAN-2000','DD-MON-YYYY'))
          TABLESPACE tbs_4
      );

CREATE TABLE shipments
( order_id      NUMBER NOT NULL
, order_date    DATE NOT NULL
, delivery_date DATE NOT NULL
, customer_id   NUMBER NOT NULL
, sales_amount  NUMBER NOT NULL
)
PARTITION BY RANGE (order_date)
SUBPARTITION BY RANGE (delivery_date)
( PARTITION p_2006_jul VALUES LESS THAN (TO_DATE('01-AUG-2006','dd-MON-yyyy'))
  ( SUBPARTITION p06_jul_e VALUES LESS THAN (TO_DATE('15-AUG-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_jul_a VALUES LESS THAN (TO_DATE('01-SEP-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_jul_l VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_2006_aug VALUES LESS THAN (TO_DATE('01-SEP-2006','dd-MON-yyyy'))
  ( SUBPARTITION p06_aug_e VALUES LESS THAN (TO_DATE('15-SEP-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_aug_a VALUES LESS THAN (TO_DATE('01-OCT-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_aug_l VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_2006_sep VALUES LESS THAN (TO_DATE('01-OCT-2006','dd-MON-yyyy'))
  ( SUBPARTITION p06_sep_e VALUES LESS THAN (TO_DATE('15-OCT-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_sep_a VALUES LESS THAN (TO_DATE('01-NOV-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_sep_l VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_2006_oct VALUES LESS THAN (TO_DATE('01-NOV-2006','dd-MON-yyyy'))
  ( SUBPARTITION p06_oct_e VALUES LESS THAN (TO_DATE('15-NOV-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_oct_a VALUES LESS THAN (TO_DATE('01-DEC-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_oct_l VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_2006_nov VALUES LESS THAN (TO_DATE('01-DEC-2006','dd-MON-yyyy'))
  ( SUBPARTITION p06_nov_e VALUES LESS THAN (TO_DATE('15-DEC-2006','dd-MON-yyyy'))
  , SUBPARTITION p06_nov_a VALUES LESS THAN (TO_DATE('01-JAN-2007','dd-MON-yyyy'))
  , SUBPARTITION p06_nov_l VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_2006_dec VALUES LESS THAN (TO_DATE('01-JAN-2007','dd-MON-yyyy'))
  ( SUBPARTITION p06_dec_e VALUES LESS THAN (TO_DATE('15-JAN-2007','dd-MON-yyyy'))
  , SUBPARTITION p06_dec_a VALUES LESS THAN (TO_DATE('01-FEB-2007','dd-MON-yyyy'))
  , SUBPARTITION p06_dec_l VALUES LESS THAN (MAXVALUE)
  )
);

CREATE TABLE accounts
( id             NUMBER
, account_number NUMBER
, customer_id    NUMBER
, balance        NUMBER
, branch_id      NUMBER
, region         VARCHAR(2)
, status         VARCHAR2(1)
)
PARTITION BY LIST (region)
SUBPARTITION BY HASH (customer_id) SUBPARTITIONS 8
( PARTITION p_northwest VALUES ('OR', 'WA')
, PARTITION p_southwest VALUES ('AZ', 'UT', 'NM')
, PARTITION p_northeast VALUES ('NY', 'VM', 'NJ')
, PARTITION p_southeast VALUES ('FL', 'GA')
, PARTITION p_northcentral VALUES ('SD', 'WI')
, PARTITION p_southcentral VALUES ('OK', 'TX')
);

CREATE TABLE accounts
( id             NUMBER
, account_number NUMBER
, customer_id    NUMBER
, balance        NUMBER
, branch_id      NUMBER
, region         VARCHAR(2)
, status         VARCHAR2(1)
)
PARTITION BY LIST (region)
SUBPARTITION BY LIST (status)
( PARTITION p_northwest VALUES ('OR', 'WA')
  ( SUBPARTITION p_nw_bad VALUES ('B')
  , SUBPARTITION p_nw_average VALUES ('A')
  , SUBPARTITION p_nw_good VALUES ('G')
  )
, PARTITION p_southwest VALUES ('AZ', 'UT', 'NM')
  ( SUBPARTITION p_sw_bad VALUES ('B')
  , SUBPARTITION p_sw_average VALUES ('A')
  , SUBPARTITION p_sw_good VALUES ('G')
  )
, PARTITION p_northeast VALUES ('NY', 'VM', 'NJ')
  ( SUBPARTITION p_ne_bad VALUES ('B')
  , SUBPARTITION p_ne_average VALUES ('A')
  , SUBPARTITION p_ne_good VALUES ('G')
  )
, PARTITION p_southeast VALUES ('FL', 'GA')
  ( SUBPARTITION p_se_bad VALUES ('B')
  , SUBPARTITION p_se_average VALUES ('A')
  , SUBPARTITION p_se_good VALUES ('G')
  )
, PARTITION p_northcentral VALUES ('SD', 'WI')
  ( SUBPARTITION p_nc_bad VALUES ('B')
  , SUBPARTITION p_nc_average VALUES ('A')
  , SUBPARTITION p_nc_good VALUES ('G')
  )
, PARTITION p_southcentral VALUES ('OK', 'TX')
  ( SUBPARTITION p_sc_bad VALUES ('B')
  , SUBPARTITION p_sc_average VALUES ('A')
  , SUBPARTITION p_sc_good VALUES ('G')
  )
);

CREATE TABLE accounts
( id             NUMBER
, account_number NUMBER
, customer_id    NUMBER
, balance        NUMBER
, branch_id      NUMBER
, region         VARCHAR(2)
, status         VARCHAR2(1)
)
PARTITION BY LIST (region)
SUBPARTITION BY RANGE (balance)
( PARTITION p_northwest VALUES ('OR', 'WA')
  ( SUBPARTITION p_nw_low VALUES LESS THAN (1000)
  , SUBPARTITION p_nw_average VALUES LESS THAN (10000)
  , SUBPARTITION p_nw_high VALUES LESS THAN (100000)
  , SUBPARTITION p_nw_extraordinary VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_southwest VALUES ('AZ', 'UT', 'NM')
  ( SUBPARTITION p_sw_low VALUES LESS THAN (1000)
  , SUBPARTITION p_sw_average VALUES LESS THAN (10000)
  , SUBPARTITION p_sw_high VALUES LESS THAN (100000)
  , SUBPARTITION p_sw_extraordinary VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_northeast VALUES ('NY', 'VM', 'NJ')
  ( SUBPARTITION p_ne_low VALUES LESS THAN (1000)
  , SUBPARTITION p_ne_average VALUES LESS THAN (10000)
  , SUBPARTITION p_ne_high VALUES LESS THAN (100000)
  , SUBPARTITION p_ne_extraordinary VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_southeast VALUES ('FL', 'GA')
  ( SUBPARTITION p_se_low VALUES LESS THAN (1000)
  , SUBPARTITION p_se_average VALUES LESS THAN (10000)
  , SUBPARTITION p_se_high VALUES LESS THAN (100000)
  , SUBPARTITION p_se_extraordinary VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_northcentral VALUES ('SD', 'WI')
  ( SUBPARTITION p_nc_low VALUES LESS THAN (1000)
  , SUBPARTITION p_nc_average VALUES LESS THAN (10000)
  , SUBPARTITION p_nc_high VALUES LESS THAN (100000)
  , SUBPARTITION p_nc_extraordinary VALUES LESS THAN (MAXVALUE)
  )
, PARTITION p_southcentral VALUES ('OK', 'TX')
  ( SUBPARTITION p_sc_low VALUES LESS THAN (1000)
  , SUBPARTITION p_sc_average VALUES LESS THAN (10000)
  , SUBPARTITION p_sc_high VALUES LESS THAN (100000)
  , SUBPARTITION p_sc_extraordinary VALUES LESS THAN (MAXVALUE)
  )
) ENABLE ROW MOVEMENT;

CREATE TABLE sales
  ( prod_id       NUMBER(6)
  , cust_id       NUMBER
  , time_id       DATE
  , channel_id    CHAR(1)
  , promo_id      NUMBER(6)
  , quantity_sold NUMBER(3)
  , amount_sold   NUMBER(10,2)
  )
 PARTITION BY RANGE (time_id) INTERVAL (NUMTOYMINTERVAL(1,'MONTH'))
 SUBPARTITION BY HASH (cust_id) SUBPARTITIONS 4
 ( PARTITION before_2000 VALUES LESS THAN (TO_DATE('01-JAN-2000','dd-MON-yyyy')))
PARALLEL;

CREATE TABLE sales
  ( prod_id       NUMBER(6)
  , cust_id       NUMBER
  , time_id       DATE
  , channel_id    CHAR(1)
  , promo_id      NUMBER(6)
  , quantity_sold NUMBER(3)
  , amount_sold   NUMBER(10,2)
  )
 PARTITION BY RANGE (time_id) INTERVAL (NUMTOYMINTERVAL(1,'MONTH'))
 SUBPARTITION BY hash(cust_id)
   SUBPARTITION template
   ( SUBPARTITION p1 TABLESPACE ts1
   , SUBPARTITION p2 TABLESPACE ts2
   , SUBPARTITION p3 TABLESPACE ts3
   , SUBPARTITION P4 TABLESPACE ts4
   )
 ( PARTITION before_2000 VALUES LESS THAN (TO_DATE('01-JAN-2000','dd-MON-yyyy'))
) PARALLEL;

CREATE TABLE sales
  ( prod_id       NUMBER(6)
  , cust_id       NUMBER
  , time_id       DATE
  , channel_id    CHAR(1)
  , promo_id      NUMBER(6)
  , quantity_sold NUMBER(3)
  , amount_sold   NUMBER(10,2)
  )
 PARTITION BY RANGE (time_id) INTERVAL (NUMTODSINTERVAL(1,'DAY'))
 SUBPARTITION BY LIST (channel_id)
   SUBPARTITION TEMPLATE
   ( SUBPARTITION p_catalog VALUES ('C')
   , SUBPARTITION p_internet VALUES ('I')
   , SUBPARTITION p_partners VALUES ('P')
   , SUBPARTITION p_direct_sales VALUES ('S')
   , SUBPARTITION p_tele_sales VALUES ('T')
   )
 ( PARTITION before_2000 VALUES LESS THAN (TO_DATE('01-JAN-2000','dd-MON-yyyy')))
PARALLEL;

CREATE TABLE sales
  ( prod_id       NUMBER(6)
  , cust_id       NUMBER
  , time_id       DATE
  , channel_id    CHAR(1)
  , promo_id      NUMBER(6)
  , quantity_sold NUMBER(3)
  , amount_sold   NUMBER(10,2)
  )
 PARTITION BY RANGE (time_id) INTERVAL (NUMTODSINTERVAL(1,'DAY'))
SUBPARTITION BY RANGE(amount_sold)
   SUBPARTITION TEMPLATE
   ( SUBPARTITION p_low VALUES LESS THAN (1000)
   , SUBPARTITION p_medium VALUES LESS THAN (4000)
   , SUBPARTITION p_high VALUES LESS THAN (8000)
   , SUBPARTITION p_ultimate VALUES LESS THAN (maxvalue)
   )
 ( PARTITION before_2000 VALUES LESS THAN (TO_DATE('01-JAN-2000','dd-MON-yyyy')))
PARALLEL;

Using Subpartition Templates to Describe Composite Partitioned Tables

You can create subpartitions in a composite partitioned table using a subpartition template. A subpartition template simplifies the specification of subpartitions by not requiring that a subpartition descriptor be specified for every partition in the table. Instead, you describe subpartitions only one time in a template, then apply that subpartition template to every partition in the table. For interval-* composite partitioned tables, the subpartition template is the only way to define subpartitions for interval partitions.

The subpartition template is used whenever a subpartition descriptor is not specified for a partition. If a subpartition descriptor is specified, then it is used instead of the subpartition template for that partition. If no subpartition template is specified, and no subpartition descriptor is supplied for a partition, then a single default subpartition is created.

CREATE TABLE emp_sub_template (deptno NUMBER, empname VARCHAR(32), grade NUMBER)
     PARTITION BY RANGE(deptno) SUBPARTITION BY HASH(empname)
     SUBPARTITION TEMPLATE
         (SUBPARTITION a TABLESPACE ts1,
          SUBPARTITION b TABLESPACE ts2,
          SUBPARTITION c TABLESPACE ts3,
          SUBPARTITION d TABLESPACE ts4
         )
    (PARTITION p1 VALUES LESS THAN (1000),
     PARTITION p2 VALUES LESS THAN (2000),
     PARTITION p3 VALUES LESS THAN (MAXVALUE)
    );

SQL> SELECT TABLESPACE_NAME, PARTITION_NAME, SUBPARTITION_NAME
  2  FROM DBA_TAB_SUBPARTITIONS WHERE TABLE_NAME='EMP_SUB_TEMPLATE'
  3  ORDER BY TABLESPACE_NAME;

TABLESPACE_NAME PARTITION_NAME  SUBPARTITION_NAME
--------------- --------------- ------------------
TS1             P1              P1_A
TS1             P2              P2_A
TS1             P3              P3_A
TS2             P1              P1_B
TS2             P2              P2_B
TS2             P3              P3_B
TS3             P1              P1_C
TS3             P2              P2_C
TS3             P3              P3_C
TS4             P1              P1_D
TS4             P2              P2_D
TS4             P3              P3_D

12 rows selected.

CREATE TABLE stripe_regional_sales
            ( deptno number, item_no varchar2(20),
              txn_date date, txn_amount number, state varchar2(2))
   PARTITION BY RANGE (txn_date)
   SUBPARTITION BY LIST (state)
   SUBPARTITION TEMPLATE 
      (SUBPARTITION northwest VALUES ('OR', 'WA') TABLESPACE tbs_1,
       SUBPARTITION southwest VALUES ('AZ', 'UT', 'NM') TABLESPACE tbs_2,
       SUBPARTITION northeast VALUES ('NY', 'VM', 'NJ') TABLESPACE tbs_3,
       SUBPARTITION southeast VALUES ('FL', 'GA') TABLESPACE tbs_4,
       SUBPARTITION midwest VALUES ('SD', 'WI') TABLESPACE tbs_5,
       SUBPARTITION south VALUES ('AL', 'AK') TABLESPACE tbs_6,
       SUBPARTITION others VALUES (DEFAULT ) TABLESPACE tbs_7
      )
  (PARTITION q1_1999 VALUES LESS THAN ( TO_DATE('01-APR-1999','DD-MON-YYYY')),
   PARTITION q2_1999 VALUES LESS THAN ( TO_DATE('01-JUL-1999','DD-MON-YYYY')),
   PARTITION q3_1999 VALUES LESS THAN ( TO_DATE('01-OCT-1999','DD-MON-YYYY')),
   PARTITION q4_1999 VALUES LESS THAN ( TO_DATE('1-JAN-2000','DD-MON-YYYY'))
  );

Using Multicolumn Partitioning Keys

For range-partitioned and hash-partitioned tables, you can specify up to 16 partitioning key columns. Use multicolumn partitioning when the partitioning key is composed of several columns and subsequent columns define a higher granularity than the preceding ones. The most common scenario is a decomposed DATE or TIMESTAMP key, consisting of separated columns, for year, month, and day.

In evaluating multicolumn partitioning keys, the database uses the second value only if the first value cannot uniquely identify a single target partition, and uses the third value only if the first and second do not determine the correct partition, and so forth. A value cannot determine the correct partition only when a partition bound exactly matches that value and the same bound is defined for the next partition. The n^th column is investigated only when all previous (n-1) values of the multicolumn key exactly match the (n-1) bounds of a partition. A second column, for example, is evaluated only if the first column exactly matches the partition boundary value. If all column values exactly match all of the bound values for a partition, then the database determines that the row does not fit in this partition and considers the next partition for a match.

For nondeterministic boundary definitions (successive partitions with identical values for at least one column), the partition boundary value becomes an inclusive value, representing a "less than or equal to" boundary. This is in contrast to deterministic boundaries, where the values are always regarded as "less than" boundaries.

Example 4-21 illustrates the column evaluation for a multicolumn range-partitioned table, storing the actual DATE information in three separate columns: year, month, and day. The partitioning granularity is a calendar quarter. The partitioned table being evaluated is created as follows:

CREATE TABLE sales_demo (
   year          NUMBER, 
   month         NUMBER,
   day           NUMBER,
   amount_sold   NUMBER) 
PARTITION BY RANGE (year,month) 
  (PARTITION before2001 VALUES LESS THAN (2001,1),
   PARTITION q1_2001    VALUES LESS THAN (2001,4),
   PARTITION q2_2001    VALUES LESS THAN (2001,7),
   PARTITION q3_2001    VALUES LESS THAN (2001,10),
   PARTITION q4_2001    VALUES LESS THAN (2002,1),
   PARTITION future     VALUES LESS THAN (MAXVALUE,0));

REM  12-DEC-2000
INSERT INTO sales_demo VALUES(2000,12,12, 1000);
REM  17-MAR-2001
INSERT INTO sales_demo VALUES(2001,3,17, 2000);
REM  1-NOV-2001
INSERT INTO sales_demo VALUES(2001,11,1, 5000);
REM  1-JAN-2002
INSERT INTO sales_demo VALUES(2002,1,1, 4000);

The year value for 12-DEC-2000 satisfied the first partition, before2001, so no further evaluation is needed:

SELECT * FROM sales_demo PARTITION(before2001);

      YEAR      MONTH        DAY AMOUNT_SOLD
---------- ---------- ---------- -----------
      2000         12         12        1000

The information for 17-MAR-2001 is stored in partition q1_2001. The first partitioning key column, year, does not by itself determine the correct partition, so the second partitioning key column, month, must be evaluated.

SELECT * FROM sales_demo PARTITION(q1_2001);

      YEAR      MONTH        DAY AMOUNT_SOLD
---------- ---------- ---------- -----------
      2001          3         17        2000

Following the same determination rule as for the previous record, the second column, month, determines partition q4_2001 as correct partition for 1-NOV-2001:

SELECT * FROM sales_demo PARTITION(q4_2001);

      YEAR      MONTH        DAY AMOUNT_SOLD
---------- ---------- ---------- -----------
      2001         11          1        5000

The partition for 01-JAN-2002 is determined by evaluating only the year column, which indicates the future partition:

SELECT * FROM sales_demo PARTITION(future);

      YEAR      MONTH        DAY AMOUNT_SOLD
---------- ---------- ---------- -----------
      2002          1          1        4000

If the database encounters MAXVALUE in one of the partitioning key columns, then all other values of subsequent columns become irrelevant. That is, a definition of partition future in the preceding example, having a bound of (MAXVALUE,0) is equivalent to a bound of (MAXVALUE,100) or a bound of (MAXVALUE,MAXVALUE).

The following example illustrates the use of a multicolumn partitioned approach for table supplier_parts, storing the information about which suppliers deliver which parts. To distribute the data in equal-sized partitions, it is not sufficient to partition the table based on the supplier_id, because some suppliers might provide hundreds of thousands of parts, while others provide only a few specialty parts. Instead, you partition the table on (supplier_id, partnum) to manually enforce equal-sized partitions.

CREATE TABLE supplier_parts (
   supplier_id      NUMBER, 
   partnum          NUMBER,
   price            NUMBER)
PARTITION BY RANGE (supplier_id, partnum)
  (PARTITION p1 VALUES LESS THAN  (10,100),
   PARTITION p2 VALUES LESS THAN (10,200),
   PARTITION p3 VALUES LESS THAN (MAXVALUE,MAXVALUE));

The following three records are inserted into the table:

INSERT INTO supplier_parts VALUES (5,5, 1000);
INSERT INTO supplier_parts VALUES (5,150, 1000);
INSERT INTO supplier_parts VALUES (10,100, 1000);

The first two records are inserted into partition p1, uniquely identified by supplier_id. However, the third record is inserted into partition p2; it matches all range boundary values of partition p1 exactly and the database therefore considers the following partition for a match. The value of partnum satisfies the criteria < 200, so it is inserted into partition p2.

SELECT * FROM supplier_parts PARTITION (p1);

SUPPLIER_ID    PARTNUM      PRICE
----------- ---------- ----------
          5          5       1000
          5        150       1000

SELECT * FROM supplier_parts PARTITION (p2);

SUPPLIER_ID    PARTNUM      PRICE
----------- ---------- ----------
          10       100       1000

Every row with supplier_id < 10 is stored in partition p1, regardless of the partnum value. The column partnum is evaluated only if supplier_id =10, and the corresponding rows are inserted into partition p1, p2, or even into p3 when partnum >=200. To achieve equal-sized partitions for ranges of supplier_parts, you could choose a composite range-hash partitioned table, range partitioned by supplier_id, hash subpartitioned by partnum.

Defining the partition boundaries for multicolumn partitioned tables must obey some rules. For example, consider a table that is range partitioned on three columns a, b, and c. The individual partitions have range values represented as follows:

P0(a0, b0, c0)
P1(a1, b1, c1)
P2(a2, b2, c2)
...
Pn(an, bn, cn)

The range values you provide for each partition must follow these rules:

• a0 must be less than or equal to a1, and a1 must be less than or equal to a2, and so on.

• If a0=a1, then b0 must be less than or equal to b1. If a0 < a1, then b0 and b1 can have any values. If a0=a1 and b0=b1, then c0 must be less than or equal to c1. If b0<b1, then c0 and c1 can have any values, and so on.

• If a1=a2, then b1 must be less than or equal to b2. If a1<a2, then b1 and b2 can have any values. If a1=a2 and b1=b2, then c1 must be less than or equal to c2. If b1<b2, then c1 and c2 can have any values, and so on.

Using Virtual Column-Based Partitioning

With partitioning, a virtual column can be used as any regular column. All partition methods are supported when using virtual columns, including interval partitioning and all different combinations of composite partitioning. A virtual column used as the partitioning column cannot use calls to a PL/SQL function.

Example 4-22 shows the sales table partitioned by range-range using a virtual column for the subpartitioning key. The virtual column calculates the total value of a sale by multiplying amount_sold and quantity_sold.

CREATE TABLE sales
  ( prod_id       NUMBER(6) NOT NULL
  , cust_id       NUMBER NOT NULL
  , time_id       DATE NOT NULL
  , channel_id    CHAR(1) NOT NULL
  , promo_id      NUMBER(6) NOT NULL
  , quantity_sold NUMBER(3) NOT NULL
  , amount_sold   NUMBER(10,2) NOT NULL
  , total_amount AS (quantity_sold * amount_sold)
  )
 PARTITION BY RANGE (time_id) INTERVAL (NUMTOYMINTERVAL(1,'MONTH'))
 SUBPARTITION BY RANGE(total_amount)
 SUBPARTITION TEMPLATE
   ( SUBPARTITION p_small VALUES LESS THAN (1000)
   , SUBPARTITION p_medium VALUES LESS THAN (5000)
   , SUBPARTITION p_large VALUES LESS THAN (10000)
   , SUBPARTITION p_extreme VALUES LESS THAN (MAXVALUE)
   )
 (PARTITION sales_before_2007 VALUES LESS THAN
        (TO_DATE('01-JAN-2007','dd-MON-yyyy'))
)
ENABLE ROW MOVEMENT
PARALLEL NOLOGGING;

As the example shows, row movement is also supported with virtual columns. If row movement is enabled, then a row migrates from one partition to another partition if the virtual column evaluates to a value that belongs to another partition.

Using Table Compression with Partitioned Tables

For heap-organized partitioned tables, you can compress some or all partitions using table compression. The compression attribute can be declared for a tablespace, a table, or a partition of a table. Whenever the compress attribute is not specified, it is inherited like any other storage attribute.

Example 4-23 creates a list-partitioned table with one compressed partition costs_old. The compression attribute for the table and all other partitions is inherited from the tablespace level.

CREATE TABLE costs_demo (
   prod_id     NUMBER(6),    time_id     DATE, 
   unit_cost   NUMBER(10,2), unit_price  NUMBER(10,2))
PARTITION BY RANGE (time_id)
   (PARTITION costs_old 
       VALUES LESS THAN (TO_DATE('01-JAN-2003', 'DD-MON-YYYY')) COMPRESS,
    PARTITION costs_q1_2003 
       VALUES LESS THAN (TO_DATE('01-APR-2003', 'DD-MON-YYYY')),
    PARTITION costs_q2_2003
       VALUES LESS THAN (TO_DATE('01-JUN-2003', 'DD-MON-YYYY')),
    PARTITION costs_recent VALUES LESS THAN (MAXVALUE));

Using Key Compression with Partitioned Indexes

You can compress some or all partitions of a B-tree index using key compression. Key compression is applicable only to B-tree indexes. Bitmap indexes are stored in a compressed manner by default. An index using key compression eliminates repeated occurrences of key column prefix values, thus saving space and I/O.

The following example creates a local partitioned index with all partitions except the most recent one compressed:

CREATE INDEX i_cost1 ON costs_demo (prod_id) COMPRESS LOCAL
   (PARTITION costs_old, PARTITION costs_q1_2003, 
    PARTITION costs_q2_2003, PARTITION costs_recent NOCOMPRESS);

You cannot specify COMPRESS (or NOCOMPRESS) explicitly for an index subpartition. All index subpartitions of a given partition inherit the key compression setting from the parent partition.

To modify the key compression attribute for all subpartitions of a given partition, you must first issue an ALTER INDEX...MODIFY PARTITION statement and then rebuild all subpartitions. The MODIFY PARTITION clause marks all index subpartitions as UNUSABLE.

Using Partitioning with Segments

This sections discusses the functionality when using partitioning with segments:

• Deferred Segment Creation for Partitioning

• Truncating Segments That Are Empty

• Maintenance Procedures for Segment Creation on Demand

Creating Partitioned Index-Organized Tables

For index-organized tables, you can use the range, list, or hash partitioning method. The semantics for creating partitioned index-organized tables is similar to that for regular tables with these differences:

• When you create the table, you specify the ORGANIZATION INDEX clause, and INCLUDING and OVERFLOW clauses as necessary.

• The PARTITION or PARTITIONS clauses can have OVERFLOW subclauses that allow you to specify attributes of the overflow segments at the partition level.

Specifying an OVERFLOW clause results in the overflow data segments themselves being equipartitioned with the primary key index segments. Thus, for partitioned index-organized tables with overflow, each partition has an index segment and an overflow data segment.

For index-organized tables, the set of partitioning columns must be a subset of the primary key columns. Because rows of an index-organized table are stored in the primary key index for the table, the partitioning criterion affects the availability. By choosing the partitioning key to be a subset of the primary key, an insert operation must only verify uniqueness of the primary key in a single partition, thereby maintaining partition independence.

Support for secondary indexes on index-organized tables is similar to the support for regular tables. Because of the logical nature of the secondary indexes, global indexes on index-organized tables remain usable for certain operations where they would be marked UNUSABLE for regular tables. For more information, refer to "Maintaining Partitions".

CREATE TABLE sales(acct_no NUMBER(5), 
                   acct_name CHAR(30), 
                   amount_of_sale NUMBER(6), 
                   week_no INTEGER,
                   sale_details VARCHAR2(1000),
             PRIMARY KEY (acct_no, acct_name, week_no)) 
     ORGANIZATION INDEX 
             INCLUDING week_no
             OVERFLOW TABLESPACE overflow_here
     PARTITION BY RANGE (week_no)
            (PARTITION VALUES LESS THAN (5) 
                   TABLESPACE ts1,
             PARTITION VALUES LESS THAN (9) 
                   TABLESPACE ts2 OVERFLOW TABLESPACE overflow_ts2,
             ...
             PARTITION VALUES LESS THAN (MAXVALUE) 
                   TABLESPACE ts13);

CREATE TABLE sales(acct_no NUMBER(5), 
                   acct_name CHAR(30), 
                   amount_of_sale NUMBER(6), 
                   week_no INTEGER,
                   sale_details VARCHAR2(1000),
             PRIMARY KEY (acct_no, acct_name, week_no)) 
     ORGANIZATION INDEX 
             INCLUDING week_no
     OVERFLOW
          PARTITION BY HASH (week_no)
             PARTITIONS 16
             STORE IN (ts1, ts2, ts3, ts4)
             OVERFLOW STORE IN (ts3, ts6, ts9);

CREATE TABLE sales(acct_no NUMBER(5), 
                   acct_name CHAR(30), 
                   amount_of_sale NUMBER(6), 
                   week_no INTEGER,
                   sale_details VARCHAR2(1000),
             PRIMARY KEY (acct_no, acct_name, week_no)) 
     ORGANIZATION INDEX 
             INCLUDING week_no
             OVERFLOW TABLESPACE example
     PARTITION BY LIST (week_no)
            (PARTITION VALUES (1, 2, 3, 4) 
                   TABLESPACE example,
             PARTITION VALUES (5, 6, 7, 8) 
                   TABLESPACE example OVERFLOW TABLESPACE example,
             PARTITION VALUES (DEFAULT) 
                   TABLESPACE example);

Partitioning Restrictions for Multiple Block Sizes

Use caution when creating partitioned objects in a database with tablespaces of different block sizes. The storage of partitioned objects in such tablespaces is subject to some restrictions. Specifically, all partitions of the following entities must reside in tablespaces of the same block size:

• Conventional tables

• Indexes

• Primary key index segments of index-organized tables

• Overflow segments of index-organized tables

• LOB columns stored out of line

Therefore:

• For each conventional table, all partitions of that table must be stored in tablespaces with the same block size.

• For each index-organized table, all primary key index partitions must reside in tablespaces of the same block size, and all overflow partitions of that table must reside in tablespaces of the same block size. However, index partitions and overflow partitions can reside in tablespaces of different block size.

• For each index (global or local), each partition of that index must reside in tablespaces of the same block size. However, partitions of different indexes defined on the same object can reside in tablespaces of different block sizes.

• For each LOB column, each partition of that column must be stored in tablespaces of equal block sizes. However, different LOB columns can be stored in tablespaces of different block sizes.

When you create or alter a partitioned table or index, all tablespaces you explicitly specify for the partitions and subpartitions of each entity must be of the same block size. If you do not explicitly specify tablespace storage for an entity, then the tablespaces the database uses by default must be of the same block size. Therefore, you must be aware of the default tablespaces at each level of the partitioned object.

Partitioning of Collections in XMLType and Objects

For the purposes of this discussion, the term Collection Tables is used for the following two categories: (1) ordered collection tables inside XMLType tables or columns, and (2) nested tables inside object tables or columns.

Partitioning when using XMLType or object tables and columns follows the basic rules for partitioning. When you partition Collection Tables, Oracle Database uses the partitioning scheme of the base table. Also, Collection Tables are automatically partitioned when the base table is partitioned. DML against a partitioned nested table behaves in a similar manner to that of a reference partitioned table.

The statement in Example 4-27 creates a nested table partition:

CREATE TABLE print_media_part (
   product_id NUMBER(6),
   ad_id NUMBER(6),
   ad_composite BLOB,
   ad_sourcetext CLOB,
   ad_finaltext CLOB,
   ad_fltextn NCLOB,
   ad_textdocs_ntab TEXTDOC_TAB,
   ad_photo BLOB,
   ad_graphic BFILE,
   ad_header ADHEADER_TYP)
NESTED TABLE ad_textdocs_ntab STORE AS textdoc_nt
PARTITION BY RANGE (product_id)
  (PARTITION p1 VALUES LESS THAN (100),
   PARTITION p2 VALUES LESS THAN (200));

For an example of issuing a query against a partitioned nested table and using the EXPLAIN PLAN to improve performance, see "Collection Tables".

Note that Oracle Database provides a LOCAL keyword to equipartition a Collection Table with a partitioned base table. This is the default behavior in this release. The default in earlier releases was not to equipartition the Collection Table with the partitioned base table. Now you must specify the GLOBAL keyword to store an unpartitioned Collection Table with a partitioned base table. See Oracle Database SQL Language Reference for more information. Also, to convert your existing nonpartitioned collection tables to partitioned, use online redefinition, as illustrated in "Redefining Partitions Online".

Out-of-line (OOL) table partitioning is supported. However, you cannot create two tables of the same XML schema that has out-of-line tables. This means that exchange partitioning cannot be performed for schemas with OOL tables because it is not possible to have two tables of the same schema.

ALTER TABLE print_media_part 
   ADD PARTITION p4 VALUES LESS THAN (400)
   LOB(ad_photo, ad_composite) STORE AS (TABLESPACE omf_ts1)
   LOB(ad_sourcetext, ad_finaltext) STORE AS (TABLESPACE omf_ts1)
   NESTED TABLE ad_textdocs_ntab STORE AS nt_p3;