随着数据库数据量的不断增长，有些表须要由普通的堆表转换为分区表的模式。有几种不同的方法来对此进行操作。诸如导出表数据，然后创建分区表再导入数据到分区表。使用EXCHANGE PARTITION方式来转换为分区表以及使用DBMS_REDEFINITION来在线重定义分区表。本文描写叙述的是使用DBMS_REDEFINITION来实现，以下是详细的操作演示样例。

      有关详细的dbms_redefinition在线重定义表的原理及步骤可參考：基于 dbms_redefinition 在线重定义表
      有关分区表的描写叙述请參考：Oracle 分区表

1、准备环境

--创建用户SQL> create user leshami identified by xxx;SQL> grant dba to leshami;--创建演示须要用到的表空间SQL> create tablespace tbs_tmp datafile ‘/u02/database/SYBO2/oradata/tbs_tmp.dbf‘ size 10m autoextend on;SQL> alter user leshami default tablespace tbs_tmp;SQL> create tablespace tbs1 datafile ‘/u02/database/SYBO2/oradata/tbs1.dbf‘ size 10m autoextend on;SQL> create tablespace tbs2 datafile ‘/u02/database/SYBO2/oradata/tbs2.dbf‘ size 10m autoextend on;SQL> create tablespace tbs3 datafile ‘/u02/database/SYBO2/oradata/tbs3.dbf‘ size 10m autoextend on;SQL> conn leshami/xxx-- 创建一个lookup表CREATE TABLE lookup (  id            NUMBER(10),  description   VARCHAR2(50));--加入主键约束ALTER TABLE lookup ADD (  CONSTRAINT lookup_pk PRIMARY KEY (id));--插入数据INSERT INTO lookup (id, description) VALUES (1, ‘ONE‘);INSERT INTO lookup (id, description) VALUES (2, ‘TWO‘);INSERT INTO lookup (id, description) VALUES (3, ‘THREE‘);COMMIT;--创建一个用于切换到分区的大表CREATE TABLE big_table (  id            NUMBER(10),  created_date  DATE,  lookup_id     NUMBER(10),  data          VARCHAR2(50));--填充数据到大表DECLARE  l_lookup_id    lookup.id%TYPE;  l_create_date  DATE;BEGIN  FOR i IN 1 .. 1000000 LOOP    IF MOD(i, 3) = 0 THEN      l_create_date := ADD_MONTHS(SYSDATE, -24);      l_lookup_id   := 2;    ELSIF MOD(i, 2) = 0 THEN      l_create_date := ADD_MONTHS(SYSDATE, -12);      l_lookup_id   := 1;    ELSE      l_create_date := SYSDATE;      l_lookup_id   := 3;    END IF;        INSERT INTO big_table (id, created_date, lookup_id, data)    VALUES (i, l_create_date, l_lookup_id, ‘This is some data for ‘ || i);  END LOOP;  COMMIT;END;/--为大表加入主、外键约束。索引。以及加入触发器等.ALTER TABLE big_table ADD (  CONSTRAINT big_table_pk PRIMARY KEY (id));CREATE INDEX bita_created_date_i ON big_table(created_date);CREATE INDEX bita_look_fk_i ON big_table(lookup_id);ALTER TABLE big_table ADD (  CONSTRAINT bita_look_fk  FOREIGN KEY (lookup_id)  REFERENCES lookup(id));CREATE OR REPLACE TRIGGER tr_bf_big_table   BEFORE UPDATE OF created_date   ON big_table   FOR EACH ROWBEGIN   :new.created_date := TO_CHAR (SYSDATE, ‘yyyymmdd hh24:mi:ss‘);END tr_bf_big_table;/--收集统计信息EXEC DBMS_STATS.gather_table_stats(‘LESHAMI‘, ‘LOOKUP‘, cascade => TRUE);EXEC DBMS_STATS.gather_table_stats(‘LESHAMI‘, ‘BIG_TABLE‘, cascade => TRUE);--表上的索引相关信息SQL> @idx_infoTABLE_NAME                INDEX_NAME                     CL_NAM                  STATUS   PAR ------------------------- ------------------------------ --------------------    -------- --- LOOKUP                    LOOKUP_PK                      ID                      VALID    NO  BIG_TABLE                 BIG_TABLE_PK                   ID                      VALID    NO BIG_TABLE                 BITA_CREATED_DATE_I            CREATED_DATE            VALID    NO BIG_TABLE                 BITA_LOOK_FK_I                 LOOKUP_ID               VALID    NO--创建一个中间表(分区表)CREATE TABLE big_table2 (  id            NUMBER(10),  created_date  DATE,  lookup_id     NUMBER(10),  data          VARCHAR2(50))PARTITION BY RANGE (created_date)(PARTITION big_table_2012 VALUES LESS THAN (TO_DATE(‘01/01/2013‘, ‘DD/MM/YYYY‘)) tablespace tbs1, PARTITION big_table_2013 VALUES LESS THAN (TO_DATE(‘01/01/2014‘, ‘DD/MM/YYYY‘)) tablespace tbs2, PARTITION big_table_2014 VALUES LESS THAN (MAXVALUE) tablespace tbs3);

2、切换普通表到分区表

----校验表是否能被重定义 EXEC DBMS_REDEFINITION.CAN_REDEF_TABLE(‘LESHAMI‘, ‘BIG_TABLE‘);--開始重定义BEGIN DBMS_REDEFINITION.start_redef_table(   uname      => ‘LESHAMI‘,           orig_table => ‘BIG_TABLE‘,   int_table  => ‘BIG_TABLE2‘);END;/--可选步骤，用于同步重定义表与暂时表  BEGIN  dbms_redefinition.sync_interim_table(    uname      => ‘LESHAMI‘,            orig_table => ‘BIG_TABLE‘,    int_table  => ‘BIG_TABLE2‘);END;/--为中间表加入对应的索引，约束等ALTER TABLE big_table2 ADD (  CONSTRAINT big_table_pk2 PRIMARY KEY (id));CREATE INDEX bita_created_date_i2 ON big_table2(created_date) LOCAL;CREATE INDEX bita_look_fk_i2 ON big_table2(lookup_id) LOCAL;ALTER TABLE big_table2 ADD (  CONSTRAINT bita_look_fk2  FOREIGN KEY (lookup_id)  REFERENCES lookup(id));--为中间表加入触发器CREATE OR REPLACE TRIGGER tr_bf_big_table2   BEFORE UPDATE OF created_date   ON big_table2   FOR EACH ROWBEGIN   :new.created_date := TO_CHAR (SYSDATE, ‘yyyymmdd hh24:mi:ss‘);END tr_bf_big_table2;/-- Gather statistics on the new table.EXEC DBMS_STATS.gather_table_stats(‘LESHAMI‘, ‘BIG_TABLE2‘, cascade => TRUE);--完毕在线重定义BEGIN  dbms_redefinition.finish_redef_table(      --Author : Leshami    uname      => ‘LESHAMI‘,                 --Blog   : http://blog.csdn.net/leshmai      orig_table => ‘BIG_TABLE‘,    int_table  => ‘BIG_TABLE2‘);END;/--能够看到新的表BIG_TABLE上的索引已经成为分区索引。如最后一列所看到的SQL> @idx_infoTABLE_NAME                     INDEX_NAME                     CL_NAM                         STATUS   PAR------------------------------ ------------------------------ ------------------------------ -------- ---BIG_TABLE                      BIG_TABLE_PK2                  ID                             VALID    NOBIG_TABLE                      BITA_LOOK_FK_I2                LOOKUP_ID                      N/A      YESBIG_TABLE                      BITA_CREATED_DATE_I2           CREATED_DATE                   N/A      YESBIG_TABLE2                     BITA_CREATED_DATE_I            CREATED_DATE                   VALID    NOBIG_TABLE2                     BIG_TABLE_PK                   ID                             VALID    NOBIG_TABLE2                     BITA_LOOK_FK_I                 LOOKUP_ID                      VALID    NOLOOKUP                         LOOKUP_PK                      ID                             VALID    NO--校验分区表SQL> select table_name, partition_name,high_value,num_rows from user_tab_partitions where table_name=‘BIG_TABLE‘;TABLE_NAME                PARTITION_NAME                 HIGH_VALUE                        NUM_ROWS------------------------- ------------------------------ ------------------------------- ----------BIG_TABLE                 BIG_TABLE_2012                 TO_DATE(‘ 2013-01-01 00:00:00‘,     333793BIG_TABLE                 BIG_TABLE_2013                 TO_DATE(‘ 2014-01-01 00:00:00‘,     332025BIG_TABLE                 BIG_TABLE_2014                 MAXVALUE                            333128

3、切换后的收尾工作

--移除中间表DROP TABLE big_table2;--依据须要能够重命名索引及约束名ALTER TABLE big_table RENAME CONSTRAINT big_table_pk2 TO big_table_pk;ALTER TABLE big_table RENAME CONSTRAINT bita_look_fk2 TO bita_look_fk;ALTER INDEX big_table_pk2 RENAME TO big_table_pk;ALTER INDEX bita_look_fk_i2 RENAME TO bita_look_fk_i;ALTER INDEX bita_created_date_i2 RENAME TO bita_created_date_i;

4、其他

--在使用DBMS_REDEFINITION期间，假设我们使用COPY_TABLE_DEPENDENTS过程，其索引依然为非分区索引--须要删除原来的索引之后，然后又一次创建为新的本地分区索引/*SQL> set timing offSQL> variable num_errors numberBEGINDBMS_REDEFINITION.COPY_TABLE_DEPENDENTS (uname=>‘LESHAMI‘, orig_table=>‘BIG_TABLE‘, int_table=>‘BIG_TABLE2‘, num_errors=>:num_errors);END;/SQL> print num_errorsNUM_ERRORS----------         0   */         ----------------------------------------------------------例如以下为使用COPY_TABLE_DEPENDENTS依赖对象之后表BIG_TABLE2多出了几个TMP$$开头的索引，可是索引依然为普通索引。而非分区索引  SQL> @idx_info2 TABLE_NAME                INDEX_NAME                     CL_NAM               CL_POS STATUS   PAR------------------------- ------------------------------ -------------------- ------ -------- ---LOOKUP                    LOOKUP_PK                      ID                        1 VALID    NOBIG_TABLE                 BIG_TABLE_PK                   ID                        1 VALID    NOBIG_TABLE                 BITA_CREATED_DATE_I            CREATED_DATE              1 VALID    NOBIG_TABLE                 BITA_LOOK_FK_I                 LOOKUP_ID                 1 VALID    NOBIG_TABLE2                TMP$$_BIG_TABLE_PK0            ID                        1 VALID    NOBIG_TABLE2                TMP$$_BITA_CREATED_DATE_I0     CREATED_DATE              1 VALID    NOBIG_TABLE2                TMP$$_BITA_LOOK_FK_I0          LOOKUP_ID                 1 VALID    NO

 5 、參考：http://www.oracle-base.com/articles/misc/partitioning-an-existing-table.php