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 ROW
BEGIN
: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_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 --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 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_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', 333793
BIG_TABLE BIG_TABLE_2013 TO_DATE(' 2014-01-01 00:00:00', 332025
BIG_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 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 */ --------------------------------------------------------
--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$$开头的索引，可是索引依然为普通索引。而非分区索引
SQL> @idx_info2
TABLE_NAME INDEX_NAME CL_NAM CL_POS STATUS PAR
------------------------- ------------------------------ -------------------- ------ -------- ---
LOOKUP LOOKUP_PK ID 1 VALID NO
BIG_TABLE BIG_TABLE_PK ID 1 VALID NO
BIG_TABLE BITA_CREATED_DATE_I CREATED_DATE 1 VALID NO
BIG_TABLE BITA_LOOK_FK_I LOOKUP_ID 1 VALID NO
BIG_TABLE2 TMP$$_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
5 、參考：http://www.oracle-base.com/articles/misc/partitioning-an-existing-table.php