【11g】创建分区

Creating Partitions

创建分区表或索引与创建非分区表或索引非常相似，但是在CREATE table语句中包含了分区子句。包含的分区子句和子句取决于希望实现的分区类型。

在常规(堆组织的)表和索引组织的表上都可以进行分区，但包含长或长RAW columns的表除外。您可以在分区表上创建非分区的全局索引、范围分区或散列分区的全局索引和本地索引。

在创建(或更改)分区表时，可以指定行移动子句(启用行移动或禁用行移动)。如果更新了行键，则此子句可以启用或禁用将行迁移到新分区。默认值是禁用行移动。

The following sections present details and examples of creating partitions for the various types of partitioned tables and indexes:

• Creating Range-Partitioned Tables and Global Indexes

• Creating Interval-Partitioned Tables

• Creating Hash-Partitioned Tables and Global Indexes

• Creating List-Partitioned Tables

• Creating Reference-Partitioned Tables

• Creating Composite Partitioned Tables

• Using Subpartition Templates to Describe Composite Partitioned Tables

• Using Multicolumn Partitioning Keys

• Using Virtual Column-Based Partitioning

• Using Table Compression with Partitioned Tables

• Using Key Compression with Partitioned Indexes

• Using Partitioning with Segments

• Creating Partitioned Index-Organized Tables

• Partitioning Restrictions for Multiple Block Sizes

• Partitioning of Collections in XMLType and Objects

See Also:

• Oracle Database Administrator's Guide for information about managing tables

• Oracle Database SQL Language Reference for the exact syntax of the partitioning clauses for creating partitioned tables and indexes, any restrictions on their use, and specific privileges required for creating and altering tables

• Oracle Database SecureFiles and Large Objects Developer's Guide for information specific to creating partitioned tables containing columns with LOBs or other objects stored as LOBs

• Oracle Database Object-Relational Developer's Guide for information specific to creating tables with object types, nested tables, or VARRAYs

Creating Range-Partitioned Tables and Global Indexes

CREATE TABLE语句的PARTITION BY RANGE子句指定要对表或索引进行范围分区。partition子句标识各个分区范围，而partition子句的可选子句可以指定特定于分区段的物理和其他属性。如果没有在分区级别上重写，分区将继承其基础表的属性。

Creating a Range-Partitioned Table

Example 4-1 创建一个包含四个分区的表，每个分区对应一个季度的销售额。sale_year、sale_month和sale_day列是分区列，它们的值构成特定行的分区键。小于子句的值确定分区边界:分区键值与子句指定的值的有序列表相比较的行存储在分区中。每个分区都有一个名称(sales_q1, sales_q2，…)，并且每个分区都包含在一个单独的表空间中 (tsa, tsb, ...).

Example 4-1 Creating a range-partitioned 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
 );

time_id=17-MAR-2006的一行将存储在分区sales_q1_2006中。

For more information, refer to "Using Multicolumn Partitioning Keys".

In Example 4-2, 前面给出的范围分区表示例增加了更多的复杂性。存储参数和LOGGINGattribute在表级指定。这些参数替换表本身从表空间级继承的相应默认值，并由范围分区继承。然而，由于第一季度业务很少，分区sales_q1_2006的存储属性被缩小了. 指定了ENABLE ROW MOVEMENT子句，以便在对键值进行更新时，允许将行自动迁移到新分区。

Example 4-2 Creating a range-partitioned table with 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)
  )
 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;

Creating a Range-Partitioned Global Index

创建范围分区全局索引的规则类似于创建范围分区表的规则。示例4-3为前面示例中创建的表在sale_month上创建范围分区的全局索引。每个索引分区都有名称，但是存储在索引的默认表空间中。

Example 4-3 Creating a range-partitioned global index table

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)
      );

Note:

如果您的企业有使用不同字符集的数据库，那么在对字符列进行分区时要小心，因为字符的排序序列在所有字符集中并不相同。有关更多信息，请参见Oracle数据库全球化支持指南。

Creating Interval-Partitioned Tables

CREATE TABLE语句的INTERVAL子句为表建立间隔分区。必须使用partition子句指定至少一个范围分区。范围分区键值确定范围分区的高值，称为转换点，数据库自动为该转换点之外的数据创建间隔分区。每个区间划分的下边界是前一个区间或区间划分的不包含上边界。

例如，如果您创建一个间隔分区表，其中包含每月的间隔，并且转换点位于2010年1月1日，那么2010年1月间隔的下界就是2010年1月1日。无论之前是否创建了2010年6月的分区，2010年7月间隔的下边界都是2010年7月1日。但是，请注意，使用分区的高或低边界超出存储范围的日期会导致错误。

例如，TO_DATE('9999-12-01'， 'YYYY-MM-DD')导致high bound为10000-01-01，如果10000超出了合法范围，则无法存储该值。

对于区间分区，分区键只能是表中的一个列名，而且必须是NUMBER或DATE类型。可选的STORE IN子句允许您指定一个或多个表空间，数据库使用循环算法将间隔分区数据存储到其中，以便随后创建间隔分区。

Example 4-4 指定具有不同间隔宽度的四个分区。它还指定在2010年1月1日的过渡点之上，创建间隔宽度为一个月的分区。

Example 4-4 Creating an interval-partitioned table

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')) );

分区p3的上界表示过渡点。p3和它下面的所有分区(本例中是p0、p1和p2)都在range区段中，而它上面的所有分区都属于interval区段。

Creating Hash-Partitioned Tables and Global Indexes

CREATE TABLE语句的PARTITION BY HASH子句标识要对表进行散列分区。然后，可以使用partition子句指定要创建的分区的数量，还可以指定要存储这些分区的表空间。或者，您可以使用PARTITION子句来命名各个分区及其表空间。

可以为哈希分区指定的惟一属性是表空间。表的所有哈希分区必须共享从表级继承的相同段属性(表空间除外)。

Creating a Hash Partitioned Table

Example 4-5 creates a hash-partitioned table. The partitioning column is id, four partitions are created and assigned system generated names, and they are placed in four named tablespaces (gear1, gear2, ...).

Example 4-5 Creating a hash-partitioned table

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

For more information, refer to "Using Multicolumn Partitioning Keys".

下面的示例演示了创建名为dept的散列分区表的两种方法。在第一个示例中，指定了分区的数量，但是为它们分配了系统生成的名称，并将它们存储在表的默认表空间中。

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

在下面的示例中，指定了各个分区的名称以及它们所驻留的表空间。每个哈希分区(段)的初始区段大小也在表级显式声明，所有分区都继承此属性。

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);

如果为这个表创建一个本地索引，那么数据库将构造索引，以便它与基础表进行等分。数据库还确保在底层表上执行维护操作时自动维护索引。下面是在表上创建本地索引的示例dept:

CREATE INDEX loc_dept_ix ON dept(deptno) LOCAL;

你可以选择的名字哈希分区和本地索引分区的表空间存储,但是如果你不这样做,然后数据库使用的名称对应的基础分区索引分区名称,并存储在相同的表空间索引分区表的分区。

Creating a Hash-Partitioned Global Index

在多用户OLTP环境中，索引中的少量叶块具有高争用性，哈希分区全局索引可以提高索引的性能。散列分区的全局索引还可以限制索引倾斜对单调增长的列值的影响。涉及索引分区键上的等号和IN谓词的查询可以有效地使用散列分区的全局索引。

创建哈希分区全局索引的语法类似于用于哈希分区表的语法。例如，例4-6中的语句创建一个散列分区的全局索引:

Example 4-6 Creating a hash-partitioned global index

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

创建列表分区的语义与创建范围分区的语义非常相似。但是，要创建列表分区，可以在create TABLE语句中指定一个PARTITION BY list子句，而PARTITION子句指定文本值列表，这些文本值是分区列的离散值，这些列限定要包含在分区中的行。对于列表分区，分区键只能是表中的一个列名。

仅在列表分区中可用，您可以使用关键字DEFAULT来描述分区的值列表。这标识一个分区，该分区容纳不映射到任何其他分区的行。

与范围分区一样，PARTITION子句的可选子句可以指定特定于分区段的物理属性和其他属性。如果没有在分区级别上重写，分区将继承父表的属性。

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.

Example 4-7 Creating a list-partitioned table

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

与范围分区不同，使用列表分区时，分区之间没有明显的顺序感。您还可以指定一个默认分区，将不映射到任何其他分区的行映射到其中。如果在前面的示例中指定了默认分区，那么状态CA将映射到该分区。

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.

Example 4-8 Creating a list-partitioned table with a default partition

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

要创建引用分区表，可以在create table语句中指定一个PARTITION BY REFERENCE子句。此子句指定引用约束的名称，该约束成为分区引用约束，用作表中引用分区的基础。必须启用和强制引用约束。

与其他分区表一样，可以指定对象级默认属性，也可以选择指定覆盖每个分区上的对象级默认值的分区描述符。

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.

Example 4-9 Creating reference-partitioned tables

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);

如果提供了分区描述符，那么所描述的分区数量必须与所引用表中的分区或子分区的数量完全相等。如果父表是复合分区表，则该表的父表的每个子分区对应一个分区;否则，表的父分区对应一个分区。

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

要创建一个复合分区表，首先使用create table语句的PARTITION by [RANGE | LIST]子句。接下来，指定一个子分区BY [RANGE | LIST | HASH]子句，它遵循与分区BY [RANGE | LIST | HASH]子句类似的语法和规则。接下来是单独的分区和子分区或子分区子句，还可以选择子分区模板子句。

Creating Composite Range-Hash Partitioned Tables

The statement in Example 4-10 creates a range-hash partitioned table. Four range partitions are created, each containing eight subpartitions. Because the subpartitions are not named, system generated names are assigned, but the STORE IN clause distributes them across the 4 specified tablespaces (ts1, ...,ts4).

Example 4-10 Creating a composite range-hash partitioned 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) 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'))
 );

The partitions of a range-hash partitioned table are logical structures only, because their data is stored in the segments of their subpartitions. As with partitions, these subpartitions share the same logical attributes. Unlike range partitions in a range-partitioned table, the subpartitions cannot have different physical attributes from the owning partition, although they are not required to reside in the same tablespace.

Attributes specified for a range partition apply to all subpartitions of that partition. You can specify different attributes for each range partition, and you can specify a STORE IN clause at the partition level if the list of tablespaces across which the subpartitions of that partition should be spread is different from those of other partitions. All of this is illustrated in the following example.

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));

To learn how using a subpartition template can simplify the specification of a composite partitioned table, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

The following statement is an example of creating a local index on the emp table where the index segments are spread across tablespaces ts7, ts8, and ts9.

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

This local index is equipartitioned with the base table as follows:

• It consists of as many partitions as the base table.

• Each index partition consists of as many subpartitions as the corresponding base table partition.

• Index entries for rows in a given subpartition of the base table are stored in the corresponding subpartition of the index.

Creating Composite Range-List Partitioned Tables

范围列表复合分区表的范围分区被描述为非复合范围分区表的范围分区。这使得PARTITION子句的可选子句可以指定特定于分区段的物理属性和其他属性，包括表空间。如果没有在分区级别上重写，分区将继承其基础表的属性。

The list subpartition descriptions, in the SUBPARTITION clauses, are described as for non-composite list partitions, except the only physical attribute that can be specified is a tablespace (optional). Subpartitions inherit all other physical attributes from the partition description.

Example 4-11 illustrates how range-list partitioning might be used. The example tracks sales data of products by quarters and within each quarter, groups it by specified states.

Example 4-11 Creating a composite range-list partitioned table

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')
         )
      );

A row is mapped to a partition by checking whether the value of the partitioning column for a row falls within a specific partition range. The row is then mapped to a subpartition within that partition by identifying the subpartition whose descriptor value list contains a value matching the subpartition column value.

For example, some sample rows are inserted as follows:

• (10, 4532130, '23-Jan-1999', 8934.10, 'WA') maps to subpartition q1_1999_northwest

• (20, 5671621, '15-May-1999', 49021.21, 'OR') maps to subpartition q2_1999_northwest

• (30, 9977612, '07-Sep-1999', 30987.90, 'FL') maps to subpartition q3_1999_southeast

• (40, 9977612, '29-Nov-1999', 67891.45, 'TX') maps to subpartition q4_1999_southcentral

• (40, 4532130, '5-Jan-2000', 897231.55, 'TX') does not map to any partition in the table and displays an error

• (50, 5671621, '17-Dec-1999', 76123.35, 'CA') does not map to any subpartition in the table and displays an error

The partitions of a range-list partitioned table are logical structures only, because their data is stored in the segments of their subpartitions. The list subpartitions have the same characteristics as list partitions. You can specify a default subpartition, just as you specify a default partition for list partitioning.

The following example creates a table that specifies a tablespace at the partition and subpartition levels. The number of subpartitions within each partition varies, and default subpartitions are specified.

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
      );

This example results in the following subpartition descriptions:

• All subpartitions inherit their physical attributes, other than tablespace, from tablespace level defaults. This is because the only physical attribute that has been specified for partitions or subpartitions is tablespace. There are no table level physical attributes specified, thus tablespace level defaults are inherited at all levels.

• The first 4 subpartitions of partition q1_1999 are all contained in tbs_1, except for the subpartition q1_others, which is stored in tbs_4and contains all rows that do not map to any of the other partitions.

• The 6 subpartitions of partition q2_1999 are all stored in tbs_2.

• The first 2 subpartitions of partition q3_1999 are all contained in tbs_3, except for the subpartition q3_others, which is stored in tbs_4and contains all rows that do not map to any of the other partitions.

• There is no subpartition description for partition q4_1999. This results in one default subpartition being created and stored in tbs_4. The subpartition name is system generated in the form SYS_SUBPn.

To learn how using a subpartition template can simplify the specification of a composite partitioned table, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Creating Composite Range-Range Partitioned Tables

范围范围复合分区表的范围分区类似于非复合范围分区表。这使得PARTITION子句的可选子句可以指定特定于分区段的物理属性和其他属性，包括表空间。如果没有在分区级别上重写，那么分区将继承其基础表的属性。

The range subpartition descriptions, in the SUBPARTITION clauses, are similar to non-composite range partitions, except the only physical attribute that can be specified is an optional tablespace. Subpartitions inherit all other physical attributes from the partition description.

Example 4-12 illustrates how range-range partitioning might be used. The example tracks shipments. The service level agreement with the customer states that every order is delivered in the calendar month after the order was placed. The following types of orders are identified:

• E (EARLY): orders that are delivered before the middle of the next month after the order was placed. These orders likely exceed customers' expectations.

• A (AGREED): orders that are delivered in the calendar month after the order was placed (but not early orders).

• L (LATE): orders that were only delivered starting the second calendar month after the order was placed.

Example 4-12 Creating a composite range-range partitioned table

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)
  )
);

A row is mapped to a partition by checking whether the value of the partitioning column for a row falls within a specific partition range. The row is then mapped to a subpartition within that partition by identifying whether the value of the subpartitioning column falls within a specific range. For example, a shipment with an order date in September 2006 and a delivery date of October 28, 2006 falls in partition p06_oct_a.

To learn how using a subpartition template can simplify the specification of a composite partitioned table, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Creating Composite List-* Partitioned Tables

The concepts of list-hash, list-list, and list-range composite partitioning are similar to the concepts for range-hash, range-list, and range-range partitioning. However, for list-* composite partitioning you specify PARTITION BY LIST to define the partitioning strategy.

The list partitions of a list-* composite partitioned table are similar to non-composite range partitioned tables. This enables optional subclauses of a PARTITION clause to specify physical and other attributes, including tablespace, specific to a partition segment. If not overridden at the partition level, then partitions inherit the attributes of their underlying table.

The subpartition descriptions, in the SUBPARTITION or SUBPARTITIONS clauses, are similar to range-* composite partitioning methods.

For more information about the subpartition definition of a list-hash composite partitioning method, refer to "Creating Composite Range-Hash Partitioned Tables". For more information about the subpartition definition of a list-list composite partitioning method, refer to "Creating Composite Range-List Partitioned Tables". For more information about the subpartition definition of a list-range composite partitioning method, refer to "Creating Composite Range-Range Partitioned Tables".

The following sections show examples for the different list-* composite partitioning methods.

Creating Composite List-Hash Partitioned Tables

Example 4-13 shows an accounts table that is list partitioned by region and subpartitioned using hash by customer identifier.

Example 4-13 Creating a composite list-hash partitioned table

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')
);

To learn how using a subpartition template can simplify the specification of a composite partitioned table, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Creating Composite List-List Partitioned Tables

Example 4-14 shows an accounts table that is list partitioned by region and subpartitioned using list by account status.

Example 4-14 Creating a composite list-list partitioned table

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')
  )
);

To learn how using a subpartition template can simplify the specification of a composite partitioned table, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Creating Composite List-Range Partitioned Tables

Example 4-15 shows an accounts table that is list partitioned by region and subpartitioned using range by account balance. Note that row movement is enabled. Subpartitions for different list partitions could have different ranges specified.

Example 4-15 Creating a composite list-range partitioned table

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;

To learn how using a subpartition template can simplify the specification of a composite partitioned table, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Creating Composite Interval-* Partitioned Tables

The concepts of interval-* composite partitioning are similar to the concepts for range-* partitioning. However, you extend the PARTITION BY RANGE clause to include the INTERVAL definition. 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 subpartitions for intervals in an interval-* partitioned table are created when the database creates the interval. You can specify the definition of future subpartitions only with a subpartition template. To learn more about how to use a subpartition template, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Creating Composite Interval-Hash Partitioned Tables

You can create an interval-hash partitioned table with multiple hash partitions using one of the following methods:

• Specify multiple hash partitions in the PARTITIONS clause.

• Use a subpartition template.

If you do not use either of these methods, then future interval partitions get only a single hash subpartition.

Example 4-16 shows the sales table, interval partitioned using monthly intervals on time_id, with hash subpartitions by cust_id. Note that this example specifies multiple hash partitions, without any specific tablespace assignment to the individual hash partitions.

Example 4-16 Creating a composite interval-hash partitioned 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) 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;

The following example shows the same sales table, interval partitioned using monthly intervals on time_id, again with hash subpartitions by cust_id. This time, however, individual hash partitions are stored in separate tablespaces. Note that the subpartition template is used to define the tablespace assignment for future hash subpartitions. To learn more about how to use a subpartition template, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

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;

Creating Composite Interval-List Partitioned Tables

The only way to define list subpartitions for future interval partitions is with the subpartition template. If you do not use the subpartitioning template, then the only subpartition that are created for every interval partition is a DEFAULT subpartition. To learn more about how to use a subpartition template, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Example 4-17 shows the sales table, interval partitioned using daily intervals on time_id, with list subpartitions by channel_id.

Example 4-17 Creating a composite interval-list partitioned 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) 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;

Creating Composite Interval-Range Partitioned Tables

The only way to define range subpartitions for future interval partitions is with the subpartition template. If you do not use the subpartition template, then the only subpartition that is created for every interval partition is a range subpartition with the MAXVALUE upper boundary. To learn more about how to use a subpartition template, see "Using Subpartition Templates to Describe Composite Partitioned Tables".

Example 4-18 shows the sales table, interval partitioned using daily intervals on time_id, with range subpartitions by amount_sold.

Example 4-18 Creating a composite interval-range partitioned 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) 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

可以使用子分区模板在复合分区表中创建子分区。子分区模板不需要为表中的每个分区指定子分区描述符，从而简化了子分区的规范。相反，在模板中只描述子分区一次，然后将该子分区模板应用于表中的每个分区。对于区间-*组合分区表，子分区模板是为区间分区定义子分区的唯一方法。

当没有为分区指定子分区描述符时，将使用子分区模板。如果指定了子分区描述符，则使用它代替该分区的子分区模板。如果没有指定子分区模板，也没有为分区提供子分区描述符，那么将创建一个默认的子分区。

Specifying a Subpartition Template for a *-Hash Partitioned Table

For range-hash, interval-hash, and list-hash partitioned tables, the subpartition template can describe the subpartitions in detail, or it can specify just the number of hash subpartitions.

Example 4-19 creates a range-hash partitioned table using a subpartition template:

Example 4-19 Creating a range-hash partitioned table with a subpartition template

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)
    );

This example produces the following table description:

• Every partition has four subpartitions as described in the subpartition template.

• Each subpartition has a tablespace specified. It is required that if a tablespace is specified for one subpartition in a subpartition template, then one must be specified for all.

• The names of the subpartitions, unless you use interval-* subpartitioning, are generated by concatenating the partition name with the subpartition name in the form:

  partition name_subpartition name

  For interval-* subpartitioning, the subpartition names are system-generated in the form:

  SYS_SUBPn

The following query displays the subpartition names and tablespaces:

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.

Specifying a Subpartition Template for a *-List Partitioned Table

Example 4-20, for a range-list partitioned table, illustrates how using a subpartition template can help you stripe data across tablespaces. In this example, a table is created where the table subpartitions are vertically striped, meaning that subpartition n from every partition is in the same tablespace.

Example 4-20 Creating a range-list partitioned table with a subpartition template

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'))
  );

If you specified the tablespaces at the partition level (for example, tbs_1 for partition q1_1999, tbs_2 for partition q2_1999, tbs_3 for partition q3_1999, and tbs_4 for partition q4_1999) and not in the subpartition template, then the table would be horizontally striped. All subpartitions would be in the tablespace of the owning partition.

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 nth 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:

Example 4-21 Creating a multicolumn range-partitioned table

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

使用分区，虚拟列可以用作任何常规列。使用虚拟列时支持所有分区方法，包括区间分区和所有不同组合的复合分区。用作分区列的虚拟列不能使用对PL/SQL函数的调用。

See Also:

Oracle Database SQL Language Reference for the syntax on how to create a virtual column

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.

Example 4-22 Creating a table with a virtual column for the subpartitioning key

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

对于堆组织的分区表，可以使用表压缩压缩部分或所有分区。可以为表空间、表或表的分区声明压缩属性。无论何时未指定compress属性，它都会像任何其他存储属性一样被继承。

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.

Example 4-23 Creating a list-partitioned table with a compressed partition

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 PARTITIONstatement and then rebuild all subpartitions. The MODIFY PARTITION clause marks all index subpartitions as UNUSABLE.

Using Partitioning with Segments

Note:

This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2).

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

Deferred Segment Creation for Partitioning

You can defer the creation of segments when creating a partitioned table until the first row is inserted into a partition. Subsequently, when the first row is inserted, segments are created for the base table partition, LOB columns, all global indexes, and local index partitions. Deferred segment creation can be controlled by the following:

• Setting the DEFERRED_SEGMENT_CREATION initialization parameter to TRUE or FALSE in the initialization parameter file.

• Setting the initialization parameter DEFERRED_SEGMENT_CREATION to TRUE or FALSE with the ALTER SESSION or ALTER SYSTEM SQL statements.

• Specifying the keywords SEGMENT CREATION IMMEDIATE or SEGMENT CREATION DEFERRED with the partition clause when issuing the CREATE TABLE SQL statement.

You can force the creation of segments for an existing created partition with the ALTER TABLE ... MODIFY PARTITION ... ALLOCATE EXTENT SQL statement. This statement allocates one extent more than the initial number of extents specified during the CREATE TABLE.

Serializable transactions do not work with deferred segment creation. Inserting data into an empty table with no segment created, or into a partition of an interval partitioned table that does not have a segment yet, causes an error.

See Also:

• Oracle Database Reference for more information about the DEFERRED_SEGMENT_CREATION initialization parameter

• Oracle Database SQL Language Reference for more information about the ALTER SESSION and ALTER SYSTEM SQL statements

• Oracle Database SQL Language Reference for more information about the keywords SEGMENT CREATION IMMEDIATE and SEGMENT CREATION DEFERRED of the CREATE TABLE SQL statement

Truncating Segments That Are Empty

You can drop empty segments in tables and table fragments with the DBMS_SPACE_ADMIN.DROP_EMPTY_SEGMENTS procedure.

In addition, if a partition or subpartition has a segment, then the truncate feature drops the segment if the DROP ALL STORAGE clause is specified with the ALTER TABLE TRUNCATE PARTITION SQL statement.

See Also:

• Oracle Database PL/SQL Packages and Types Reference for more information about the DBMS_SPACE_ADMIN package

• Oracle Database SQL Language Reference for more information about the DROP ALL STORAGE clause of ALTER TABLE

Maintenance Procedures for Segment Creation on Demand

You can use the MATERIALIZE_DEFERRED_SEGMENTS procedure in the DBMS_SPACE_ADMIN package to create segments for tables and dependent objects for tables with the deferred segment property.

You can also force the creation of segments for an existing created table and table fragment with the DBMS_SPACE_ADMIN.MATERIALIZE_DEFERRED_SEGMENTS procedure. The MATERIALIZE_DEFERRED_SEGMENTS procedure differs from the ALTER TABLE ... MODIFY PARTITION ... ALLOCATE EXTENT SQL statement because it does not allocate one additional extent for the table or table fragment.

See Also:

• Oracle Database PL/SQL Packages and Types Reference for more information about the DBMS_SPACE_ADMIN package

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".

See Also:

• Oracle Database Administrator's Guide for more information about managing index-organized tables

• Oracle Database Concepts for more information about index-organized tables

Creating Range-Partitioned Index-Organized Tables

You can partition index-organized tables, and their secondary indexes, by the range method. In Example 4-24, a range-partitioned index-organized table sales is created. The INCLUDING clause specifies that all columns after week_no are to be stored in an overflow segment. There is one overflow segment for each partition, all stored in the same tablespace (overflow_here). Optionally, OVERFLOW TABLESPACEcould be specified at the individual partition level, in which case some or all of the overflow segments could have separate TABLESPACEattributes.

Example 4-24 Creating a range-partitioned index-organized table

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);

Creating Hash-Partitioned Index-Organized Tables

Another option for partitioning index-organized tables is to use the hash method. In Example 4-25, the sales index-organized table is partitioned by the hash method.

Example 4-25 Creating a hash-partitioned index-organized table

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);

Note:

A well-designed hash function is intended to distribute rows in a well-balanced fashion among the partitions. Therefore, updating the primary key column(s) of a row is very likely to move that row to a different partition. Oracle recommends that you explicitly specify the ENABLE ROW MOVEMENT clause when creating a hash-partitioned index-organized table with a changeable partitioning key. The default is that ENABLE ROW MOVEMENT is disabled.

Creating List-Partitioned Index-Organized Tables

The other option for partitioning index-organized tables is to use the list method. In the following example, the sales index-organized table is partitioned by the list method. Example 4-26 uses the example tablespace, which is part of the sample schemas in your seed database. Normally you would specify different tablespace storage for different partitions.

Example 4-26 Creating a list-partitioned index-organized table

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:

Example 4-27 Creating 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.

Performing PMOs on Partitions that Contain Collection Tables

Whether a partition contains Collection Tables or not does not significantly affect your ability to perform partition maintenance operations (PMOs). Usually, maintenance operations on Collection Tables are carried out on the base table. The following example illustrates a typical ADDPARTITION operation based on the preceding nested table partition:

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;

The storage table for nested table storage column ad_textdocs_ntab is named nt_p3 and inherits all other attributes from the table-level defaults and then from the tablespace defaults.

You must directly invoke the following partition maintenance operations on the storage table corresponding to the collection column:

• modify partition

• move partition

• rename partition

• modify the default attributes of a partition

See Also:

Oracle Database SQL Language Reference for syntax and Table 4-1, "ALTER TABLE Maintenance Operations for Table Partitions"for a list of partition maintenance operations that can be performed on partitioned tables and composite partitioned tables