参考分区的DEPENDENT TABLE语句

11G Oracle新增了参考分区，使得主表和子表可以根据主表上的列实现等同分区。
由于参考分区的分区操作都是在主表上进行，而子表会根据主表的分区操作自动进行，所以Oracle提供了DEPENDENT TABLE语句来设置子表的分区存储语句。
看一个简单的例子：

SQL> CREATE TABLE T_PRIMARY 
  2  (
  3     OWNER VARCHAR2(30), 
  4     TABLE_NAME VARCHAR2(30), 
  5     TABLESPACE_NAME VARCHAR2(30), 
  6     STATUS VARCHAR2(18),
  7     CONSTRAINT PK_T_PRIMARY PRIMARY KEY (OWNER, TABLE_NAME)
  8  )
  9  PARTITION BY LIST (TABLESPACE_NAME)
 10  (
 11  PARTITION P1 VALUES ('SYSTEM'), 
 12  PARTITION P2 VALUES ('YANGTK'), 
 13  PARTITION P3 VALUES ('SYSAUX'), 
 14  PARTITION P4 VALUES (DEFAULT)
 15  );
表已创建。
SQL> CREATE TABLE T_FOREIGN 
  2  (
  3  OWNER VARCHAR2(30) NOT NULL, 
  4  TABLE_NAME VARCHAR2(30) NOT NULL, 
  5  PARTITION_NAME VARCHAR2(30), 
  6  SUBPARTITION_NAME VARCHAR2(30), 
  7  NUM_ROWS NUMBER, 
  8  BLOCKS NUMBER,
  9  CONSTRAINT FK_T_FOREIGN FOREIGN KEY (OWNER, TABLE_NAME)
 10  REFERENCES T_PRIMARY (OWNER, TABLE_NAME)
 11  )
 12  PARTITION BY REFERENCE (FK_T_FOREIGN);
表已创建。
SQL> SELECT TABLE_NAME, PARTITION_NAME, TABLESPACE_NAME
  2  FROM USER_TAB_PARTITIONS
  3  WHERE TABLE_NAME IN ('T_PRIMARY', 'T_FOREIGN');
TABLE_NAME                     PARTITION_NAME                 TABLESPACE_NAME
------------------------------ ------------------------------ ------------------------------
T_PRIMARY                      P1                             USERS
T_PRIMARY                      P2                             USERS
T_PRIMARY                      P3                             USERS
T_PRIMARY                      P4                             USERS
T_FOREIGN                      P1                             USERS
T_FOREIGN                      P2                             USERS
T_FOREIGN                      P3                             USERS
T_FOREIGN                      P4                             USERS
已选择8行。

子表根据主表的TABLESPACE_NAME列实现了等同分区，如果合并P3和P4分区：

SQL> ALTER TABLE T_PRIMARY
  2  MERGE PARTITIONS P3, P4
  3  INTO PARTITION P3
  4  TABLESPACE YANGTK;
表已更改。
SQL> SELECT TABLE_NAME, PARTITION_NAME, TABLESPACE_NAME
  2  FROM USER_TAB_PARTITIONS
  3  WHERE TABLE_NAME IN ('T_PRIMARY', 'T_FOREIGN');
TABLE_NAME                     PARTITION_NAME                 TABLESPACE_NAME
------------------------------ ------------------------------ ------------------------------
T_PRIMARY                      P1                             USERS
T_PRIMARY                      P2                             USERS
T_PRIMARY                      P3                             YANGTK
T_FOREIGN                      P1                             USERS
T_FOREIGN                      P2                             USERS
T_FOREIGN                      P3                             YANGTK
已选择6行。

可以看到，如果不明确指定子表的存储参数，则默认情况下子表的分区依赖主表的分区设置，下面是一个使用DEPENTENT TABLE明确指出子表存储语句的例子：

SQL> ALTER TABLE T_PRIMARY  
  2  MERGE PARTITIONS P2, P3
  3  INTO PARTITION P2
  4  TABLESPACE YANGTK
  5  DEPENDENT TABLES (T_FOREIGN(PARTITION PF_2 TABLESPACE TEST));
表已更改。
SQL> SELECT TABLE_NAME, PARTITION_NAME, TABLESPACE_NAME
  2  FROM USER_TAB_PARTITIONS
  3  WHERE TABLE_NAME IN ('T_PRIMARY', 'T_FOREIGN');
TABLE_NAME                     PARTITION_NAME                 TABLESPACE_NAME
------------------------------ ------------------------------ ------------------------------
T_PRIMARY                      P1                             USERS
T_PRIMARY                      P2                             YANGTK
T_FOREIGN                      P1                             USERS
T_FOREIGN                      PF_2                           TEST

DEPENDENT TABLES语句可以同时指定多个表的多个分区，下面看一个复杂一点的例子：

SQL> CREATE TABLE T_FOREIGN2 
  2  (
  3  OWNER VARCHAR2(30) NOT NULL, 
  4  TABLE_NAME VARCHAR2(30) NOT NULL, 
  5  SEGMENT_NAME VARCHAR2(30),
  6  BYTES NUMBER,
  7  CONSTRAINT FK_T_FOREIGN2 FOREIGN KEY (OWNER, TABLE_NAME)
  8  REFERENCES T_PRIMARY (OWNER, TABLE_NAME)
  9  )
 10  PARTITION BY REFERENCE (FK_T_FOREIGN2);
表已创建。
SQL> SELECT TABLE_NAME, PARTITION_NAME, TABLESPACE_NAME
  2  FROM USER_TAB_PARTITIONS
  3  WHERE TABLE_NAME IN ('T_PRIMARY', 'T_FOREIGN', 'T_FOREIGN2');
TABLE_NAME                     PARTITION_NAME                 TABLESPACE_NAME
------------------------------ ------------------------------ ------------------------------
T_PRIMARY                      P1                             USERS
T_PRIMARY                      P2                             YANGTK
T_FOREIGN                      P1                             USERS
T_FOREIGN                      PF_2                           TEST
T_FOREIGN2                     P1                             USERS
T_FOREIGN2                     P2                             YANGTK
已选择6行。

下面对T_PRIMARY表执行SPLIT操作：

SQL> ALTER TABLE T_PRIMARY 
  2  SPLIT PARTITION P2 
  3  VALUES ('YANGTK') 
  4  INTO (PARTITION P2 TABLESPACE YANGTK, 
  5  PARTITION P3 TABLESPACE TEST)
  6  DEPENDENT TABLES 
  7  (T_FOREIGN(PARTITION P2 TABLESPACE TEST, 
  8  PARTITION P3 TABLESPACE USERS), 
  9  T_FOREIGN2(PARTITION P22 TABLESPACE USERS, 
 10  PARTITION P23 TABLESPACE YANGTK));
表已更改。
SQL> SELECT TABLE_NAME, PARTITION_NAME, TABLESPACE_NAME
  2  FROM USER_TAB_PARTITIONS
  3  WHERE TABLE_NAME IN ('T_PRIMARY', 'T_FOREIGN', 'T_FOREIGN2');
TABLE_NAME                     PARTITION_NAME                 TABLESPACE_NAME
------------------------------ ------------------------------ ------------------------------
T_PRIMARY                      P1                             USERS
T_PRIMARY                      P2                             YANGTK
T_PRIMARY                      P3                             TEST
T_FOREIGN                      P1                             USERS
T_FOREIGN                      P2                             TEST
T_FOREIGN                      P3                             USERS
T_FOREIGN2                     P1                             USERS
T_FOREIGN2                     P22                            USERS
T_FOREIGN2                     P23                            YANGTK
已选择9行。