隨著資料庫資料量的不斷增長，有些表需要由普通的堆錶轉換為分割槽表的模式。有幾種不同的方法來對此進行操作，諸如匯出表資料，然後建立分割槽表再匯入資料到分割槽表；使用EXCHANGE PARTITION方式來轉換為分割槽表以及使用DBMS_REDEFINITION來線上重定義分割槽表。本文描述的是使用DBMS_REDEFINITION來實現，下面是具體的操作示例。

1、準備環境

--建立使用者
SQL> create user leshami identified by xxx;

SQL> grant dba to leshami;

--建立演示需要用到的表空間
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

-- 建立一個lookup表
CREATE TABLE lookup (
  id            NUMBER(10),
  description   VARCHAR2(50)
);

--新增主鍵約束
ALTER TABLE lookup ADD (
  CONSTRAINT lookup_pk PRIMARY KEY (id)
);

--插入資料
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;

--建立一個用於切換到分割槽的大表
CREATE TABLE big_table (
  id            NUMBER(10),
  created_date  DATE,
  lookup_id     NUMBER(10),
  data          VARCHAR2(50)
);

--填充資料到大表
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;
/

--為大表新增主、外來鍵約束，索引，以及新增觸發器等.
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 ROW
BEGIN
   :new.created_date := TO_CHAR (SYSDATE, 'yyyymmdd hh24:mi:ss');
END tr_bf_big_table;
/

--收集統計資訊
EXEC DBMS_STATS.gather_table_stats('LESHAMI', 'LOOKUP', cascade => TRUE);
EXEC DBMS_STATS.gather_table_stats('LESHAMI', 'BIG_TABLE', cascade => TRUE);

--表上的索引相關資訊
SQL> @idx_info
TABLE_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

--建立一箇中間表(分割槽表)
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、切換普通表到分割槽表

----校驗表能否被重定義 
EXEC DBMS_REDEFINITION.CAN_REDEF_TABLE('LESHAMI', 'BIG_TABLE');

--開始重定義
BEGIN
 DBMS_REDEFINITION.start_redef_table(
   uname      => 'LESHAMI',        
   orig_table => 'BIG_TABLE',
   int_table  => 'BIG_TABLE2');
END;
/

--可選步驟，用於同步重定義表與臨時表  
BEGIN
  dbms_redefinition.sync_interim_table(
    uname      => 'LESHAMI',        
    orig_table => 'BIG_TABLE',
    int_table  => 'BIG_TABLE2');
END;
/

--為中間表新增相應的索引，約束等
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)
);

--為中間表新增觸發器
CREATE OR REPLACE TRIGGER tr_bf_big_table2
   BEFORE UPDATE OF created_date
   ON big_table2
   FOR EACH ROW
BEGIN
   :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);

--完成線上重定義
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;
/

--可以看到新的表BIG_TABLE上的索引已經成為分割槽索引，如最後一列所示
SQL> @idx_info

TABLE_NAME                     INDEX_NAME                     CL_NAM                         STATUS   PAR
------------------------------ ------------------------------ ------------------------------ -------- ---
BIG_TABLE                      BIG_TABLE_PK2                  ID                             VALID    NO
BIG_TABLE                      BITA_LOOK_FK_I2                LOOKUP_ID                      N/A      YES
BIG_TABLE                      BITA_CREATED_DATE_I2           CREATED_DATE                   N/A      YES
BIG_TABLE2                     BITA_CREATED_DATE_I            CREATED_DATE                   VALID    NO
BIG_TABLE2                     BIG_TABLE_PK                   ID                             VALID    NO
BIG_TABLE2                     BITA_LOOK_FK_I                 LOOKUP_ID                      VALID    NO
LOOKUP                         LOOKUP_PK                      ID                             VALID    NO

--校驗分割槽表
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',     333793
BIG_TABLE                 BIG_TABLE_2013                 TO_DATE(' 2014-01-01 00:00:00',     332025
BIG_TABLE                 BIG_TABLE_2014                 MAXVALUE                            333128

 

3、切換後的收尾工作

--移除中間表
DROP TABLE big_table2;

--根據需要可以重新命名索引及約束名
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、其它

--在使用DBMS_REDEFINITION期間，如果我們使用COPY_TABLE_DEPENDENTS過程，其索引依舊為非分割槽索引
--需要刪除原來的索引之後，然後重新建立為新的本地分割槽索引
/*SQL> set timing off
SQL> variable num_errors number

BEGIN
DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS
 (uname=>'LESHAMI',
 orig_table=>'BIG_TABLE',
 int_table=>'BIG_TABLE2',
 num_errors=>:num_errors);
END;
/

SQL> print num_errors

NUM_ERRORS
----------
         0   */
         
--------------------------------------------------------
--如下為使用COPY_TABLE_DEPENDENTS依賴物件之後表BIG_TABLE2多出了幾個TMP$$開頭的索引，但是索引依舊為普通索引，而非分割槽索引  
SQL> @idx_info2 
TABLE_NAME                INDEX_NAME                     CL_NAM               CL_POS STATUS   PAR
------------------------- ------------------------------ -------------------- ------ -------- ---
LOOKUP                    LOOKUP_PK                      ID                        1 VALID    NO
BIG_TABLE                 BIG_TABLE_PK                   ID                        1 VALID    NO
BIG_TABLE                 BITA_CREATED_DATE_I            CREATED_DATE              1 VALID    NO
BIG_TABLE                 BITA_LOOK_FK_I                 LOOKUP_ID                 1 VALID    NO
BIG_TABLE2                TMP$$_BIG_TABLE_PK0            ID                        1 VALID    NO
BIG_TABLE2                TMP$$_BITA_CREATED_DATE_I0     CREATED_DATE              1 VALID    NO
BIG_TABLE2                TMP$$_BITA_LOOK_FK_I0          LOOKUP_ID                 1 VALID    NO