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一、DBMS_REDEFINITION（在線重定義）
參考MOS文檔：_How To Partition Existing Table Using DBMS_REDEFINITION (Doc ID 472449.1)??_
支持的數據庫版本：Oracle Database - Enterprise Edition -?Version 9.2.0.4 and later
在線重定義是通過?物化視圖?實現的。
使用在線重定義的一些限制條件：
- 1、必須有足夠的表空間來容納表的兩倍數據量。
- 2、主鍵列不能被修改。
- 3、表必須有主鍵。
- 4、必須在同一個用戶下進行在線重定義。
- 5、SYS和SYSTEM用戶下的表無法進行在線重定義。
- 6、在線重定義無法采用nologging。
- 7、如果中間表有新增列，則不能有NOT NULL約束
DBMS_REDEFINITION包：
- ABSORT_REDEF_TABLE：清理重定義的錯誤和中止重定義；
- CAN_REDEF_TABLE：檢查表是否可以進行重定義,存儲過程執行成功代表可以進行重定義；
- COPY_TABLE_DEPENDENTS：同步索引和依賴的對象（包括索引、約束、觸發器、權限等）；
- FINISH_REDEF_TABLE：完成在線重定義；
- REGISTER_DEPENDENTS_OBJECTS：注冊依賴的對象，如索引、約束、觸發器等；
- START_REDEF_TABLE：開始在線重定義；
- SYNC_INTERIM_TABLE：增量同步數據；
- UNREGISTER_DEPENDENT_OBJECT：不注冊依賴的對象，如索引、約束、觸發器等；
CREATE OR REPLACE PACKAGE SYS.dbms_redefinition AUTHID CURRENT_USER IS
------------
-- OVERVIEW
--
-- This package provides the API to perform an online, out-of-place
-- redefinition of a table
--- =========
--- CONSTANTS
--- =========
-- Constants for the options_flag parameter of start_redef_table
cons_use_pk CONSTANT PLS_INTEGER := 1;
cons_use_rowid CONSTANT PLS_INTEGER := 2;
-- Constants used for the object types in the register_dependent_object
cons_index CONSTANT PLS_INTEGER := 2;
cons_constraint CONSTANT PLS_INTEGER := 3;
cons_trigger CONSTANT PLS_INTEGER := 4;
cons_mvlog CONSTANT PLS_INTEGER := 10;
-- constants used to specify the method of copying indexes
cons_orig_params CONSTANT PLS_INTEGER := 1;
PRAGMA SUPPLEMENTAL_LOG_DATA(default, AUTO_WITH_COMMIT);
-- NAME: can_redef_table - check if given table can be re-defined
-- INPUTS: uname - table owner name
-- tname - table name
-- options_flag - flag indicating user options to use
-- part_name - partition name
PROCEDURE can_redef_table(uname IN VARCHAR2,
tname IN VARCHAR2,
options_flag IN PLS_INTEGER := 1,
part_name IN VARCHAR2 := NULL);
PRAGMA SUPPLEMENTAL_LOG_DATA(can_redef_table, NONE);
-- NAME: start_redef_table - start the online re-organization
-- INPUTS: uname - schema name
-- orig_table - name of table to be re-organized
-- int_table - name of interim table
-- col_mapping - select list col mapping
-- options_flag - flag indicating user options to use
-- orderby_cols - comma separated list of order by columns
-- followed by the optional ascending/descending
-- keyword
-- part_name - name of the partition to be redefined
PROCEDURE start_redef_table(uname IN VARCHAR2,
orig_table IN VARCHAR2,
int_table IN VARCHAR2,
col_mapping IN VARCHAR2 := NULL,
options_flag IN BINARY_INTEGER := 1,
orderby_cols IN VARCHAR2 := NULL,
part_name IN VARCHAR2 := NULL);
-- NAME: finish_redef_table - complete the online re-organization
-- INPUTS: uname - schema name
-- orig_table - name of table to be re-organized
-- int_table - name of interim table
-- part_name - name of the partition being redefined
PROCEDURE finish_redef_table(uname IN VARCHAR2,
orig_table IN VARCHAR2,
int_table IN VARCHAR2,
part_name IN VARCHAR2 := NULL);
-- NAME: abort_redef_table - clean up after errors or abort the
-- online re-organization
-- INPUTS: uname - schema name
-- orig_table - name of table to be re-organized
-- int_table - name of interim table
-- part_name - name of the partition being redefined
PROCEDURE abort_redef_table(uname IN VARCHAR2,
orig_table IN VARCHAR2,
int_table IN VARCHAR2,
part_name IN VARCHAR2 := NULL);
-- NAME: sync_interim_table - synchronize interim table with the original
-- table
-- INPUTS: uname - schema name
-- orig_table - name of table to be re-organized
-- int_table - name of interim table
-- part_name - name of the partition being redefined
PROCEDURE sync_interim_table(uname IN VARCHAR2,
orig_table IN VARCHAR2,
int_table IN VARCHAR2,
part_name IN VARCHAR2 := NULL);
-- NAME: register_dependent_object - register dependent object
--
-- INPUTS: uname - schema name
-- orig_table - name of table to be re-organized
-- int_table - name of interim table
-- dep_type - type of the dependent object
-- dep_owner - name of the dependent object owner
-- dep_orig_name- name of the dependent object defined on table
-- being re-organized
-- dep_int_name - name of the corressponding dependent object on
-- the interim table
PROCEDURE register_dependent_object(uname IN VARCHAR2,
orig_table IN VARCHAR2,
int_table IN VARCHAR2,
dep_type IN PLS_INTEGER,
dep_owner IN VARCHAR2,
dep_orig_name IN VARCHAR2,
dep_int_name IN VARCHAR2);
-- NAME: unregister_dependent_object - unregister dependent object
--
-- INPUTS: uname - schema name
-- orig_table - name of table to be re-organized
-- int_table - name of interim table
-- dep_type - type of the dependent object
-- dep_owner - name of the dependent object owner
-- dep_orig_name- name of the dependent object defined on table
-- being re-organized
-- dep_int_name - name of the corressponding dependent object on
-- the interim table
PROCEDURE unregister_dependent_object(uname IN VARCHAR2,
orig_table IN VARCHAR2,
int_table IN VARCHAR2,
dep_type IN PLS_INTEGER,
dep_owner IN VARCHAR2,
dep_orig_name IN VARCHAR2,
dep_int_name IN VARCHAR2);
-- NAME: copy_table_dependents
--
-- INPUTS: uname - schema name
-- orig_table - name of table to be re-organized
-- int_table - name of interim table
-- copy_indexes - integer value indicating whether to
-- copy indexes
-- 0 - don't copy
-- 1 - copy using storage params/tablespace
-- of original index
-- copy_triggers - TRUE implies copy triggers, FALSE otherwise
-- copy_constraints - TRUE implies copy constraints, FALSE
-- otherwise
-- copy_privileges - TRUE implies copy privileges, FALSE
-- otherwise
-- ignore errors - TRUE implies continue after errors, FALSE
-- otherwise
-- num_errors - number of errors that occurred while
-- cloning ddl
-- copy_statistics - TRUE implies copy table statistics, FALSE
-- otherwise.
-- If copy_indexes is 1, copy index
-- related statistics, 0 otherwise.
-- copy_mvlog - TRUE implies copy table's MV log, FALSE
-- otherwise.
PROCEDURE copy_table_dependents(uname IN VARCHAR2,
orig_table IN VARCHAR2,
int_table IN VARCHAR2,
copy_indexes IN PLS_INTEGER := 1,
copy_triggers IN BOOLEAN := TRUE,
copy_constraints IN BOOLEAN := TRUE,
copy_privileges IN BOOLEAN := TRUE,
ignore_errors IN BOOLEAN := FALSE,
num_errors OUT PLS_INTEGER,
copy_statistics IN BOOLEAN := FALSE,
copy_mvlog IN BOOLEAN := FALSE);
END;
二、在線重定義表的步驟
1.創建未分區的表
創建未分區的表，如果存在，就不需要操作。
--前置準備：創建用戶，表空間，授權用戶。
SQL> create tablespace PARTITION;
SQL> create user par identified by par;
SQL> grant dba to par;
--創建表,索引，授權，同義詞
SQL> conn par/par
Connected.
-- Create table
create table student(
s_id number(8) PRIMARY KEY,
s_name varchar2(20) not null,
s_sex varchar2(8),
s_birdate date,
constraint u_1 unique(s_name),
constraint c_1 check (s_sex in ('MALE','FEMALE')))
tablespace PARTITION;
-- Add comments to the table
comment on table STUDENT is '學生表';
-- Add comments to the columns
comment on column STUDENT.s_name is '姓名';
comment on column STUDENT.s_sex is '性別';
comment on column STUDENT.s_birdate is '出生日期';
-- Create/Recreate indexes
create index S_NAME_IDX on STUDENT (S_NAME, S_SEX) tablespace PARTITION;
-- Create SYNONYM
CREATE SYNONYM stu FOR student;
-- Grant/Revoke object privileges
grant select, insert, delete on STUDENT to SCOTT;
--查看表結構
SQL> desc stu
Name Null? Type
----------------------------------------- -------- ----------------------------
S_ID NOT NULL NUMBER(8)
S_NAME NOT NULL VARCHAR2(20)
S_SEX VARCHAR2(8)
S_BIRDATE DATE
--插入數據
begin
for i in 0 .. 24 loop
insert into student values
(i,
'student_' || i,
decode(mod(i, 2), 0, 'MALE', 'FEMALE'),
add_months(to_date('2019-1-1', 'yyyy-mm-dd'), i));
end loop;
commit;
end;
/
2.確認表是否存在主鍵，表空間是否足夠，收集表統計信息。
--查看表主鍵
SQL> select cu.* from user_cons_columns cu, user_constraints au where cu.constraint_name = au.constraint_name and au.constraint_type = 'P' and au.table_name = 'STUDENT';
--查看表大小和表空間
--查看表空間
SQL> select tablespace_name from dba_segments where segment_type= 'TABLE' and segment_name='STUDENT' and owner='PAR';
--查看表大小
SQL> select sum(bytes/1024/1024) from dba_segments where segment_type= 'TABLE' and segment_name='STUDENT' and owner='PAR';
--查看表空間
select tbs_used_info.tablespace_name,
tbs_used_info.alloc_mb,
tbs_used_info.used_mb,
tbs_used_info.max_mb,
tbs_used_info.free_of_max_mb,
tbs_used_info.used_of_max || '%' used_of_max_pct
from (select a.tablespace_name,
round(a.bytes_alloc / 1024 / 1024) alloc_mb,
round((a.bytes_alloc - nvl(b.bytes_free,
0)) / 1024 / 1024) used_mb,
round((a.bytes_alloc - nvl(b.bytes_free,
0)) * 100 / a.maxbytes) used_of_max,
round((a.maxbytes - a.bytes_alloc + nvl(b.bytes_free,
0)) / 1048576) free_of_max_mb,
round(a.maxbytes / 1048576) max_mb
from (select f.tablespace_name,
sum(f.bytes) bytes_alloc,
sum(decode(f.autoextensible,
'YES',
f.maxbytes,
'NO',
f.bytes)) maxbytes
from dba_data_files f
group by tablespace_name) a,
(select f.tablespace_name,
sum(f.bytes) bytes_free
from dba_free_space f
group by tablespace_name) b
where a.tablespace_name = b.tablespace_name(+)) tbs_used_info
order by tbs_used_info.used_of_max desc;
--如果表空間不夠，提前增加表空間大小
alter tablespace PARTITION add datafile;
--收集統計信息(可忽略)
EXEC DBMS_STATS.gather_table_stats('PAR', 'STUDENT', cascade => TRUE);
3.調用DBMS_REDEFINITION.CAN_REDEF_TABLE()
調用DBMS_REDEFINITION.CAN_REDEF_TABLE()過程，確認表是否滿足重定義的條件。
SQL> EXEC Dbms_Redefinition.can_redef_table('PAR', 'STUDENT');
PL/SQL procedure successfully completed.
4.建立一個空的中間表
在用一個用戶中建立一個空的中間表，根據重定義后你期望得到的結構建立中間表。比如：采用分區表（間隔分區），增加了COLUMN等。
在中間表上建立觸發器、索引和約束，并進行相應的授權。任何包含中間表的完整性約束應將狀態置為disabled。(此步驟也可以放在同步數據后操作)
--創建間隔分區(增加列s_phone)
create table STUDENT_PAR
(
s_id NUMBER(8) not null,
s_name VARCHAR2(20) not null,
s_sex VARCHAR2(8),
s_birdate DATE,
s_phone number
)
tablespace PARTITION
PARTITION BY RANGE(s_birdate)
INTERVAL (NUMTOYMINTERVAL(1,'MONTH')) STORE IN (partition)
(PARTITION STUDENT_201901 VALUES LESS THAN (TO_DATE('2019-02-01 00:00:00', 'SYYYY-MM-DD Hh34:MI:SS', 'NLS_CALENDAR=GREGORIAN')));
--臨時中間表上創建如下：
--創建主鍵約束
alter table STUDENT_PAR add primary key (S_ID) using index tablespace PARTITION;
--創建唯一索引約束
alter table STUDENT_PAR add constraint U_1_PAR unique (S_NAME) using index tablespace PARTITION;
--創建check約束
alter table STUDENT_PAR add constraint C_1_PAR check (s_sex in ('MALE','FEMALE'));
--創建索引
CREATE INDEX S_NAME_IDX_PAR ON STUDENT_PAR (S_NAME,S_SEX) tablespace PARTITION;
--創建同義詞
CREATE SYNONYM stu_par FOR STUDENT_PAR;
--添加描述
COMMENT ON TABLE STUDENT_PAR IS '學生表';
COMMENT ON COLUMN STUDENT_PAR.s_name IS '姓名';
COMMENT ON COLUMN STUDENT_PAR.s_sex IS '性別';
COMMENT ON COLUMN STUDENT_PAR.s_birdate IS '出生日期';
--授權
GRANT SELECT,INSERT,DELETE ON STUDENT_PAR TO scott;
5.調用DBMS_REDEFINITION.START_REDEF_TABLE
調用DBMS_REDEFINITION.START_REDEF_TABLE()過程，并提供下列參數：被重定義的表的名稱、中間表的名稱、列的映射規則、重定義方法。
如果映射方法沒有提供，則認為所有包括在中間表中的列用于表的重定義。如果給出了映射方法，則只考慮映射方法中給出的列。如果沒有給出重定義方法，則默認使用主鍵方式。
SQL> BEGIN
DBMS_REDEFINITION.start_redef_table(
uname => 'PAR',
orig_table => 'STUDENT',
int_table => 'STUDENT_PAR');
END;
/
PL/SQL procedure successfully completed.
6.（可選）在創建索引之前將新表與臨時名稱同步
Notes：如果在執行DBMS_REDEFINITION.START_REDEF_TABLE()過程和執行DBMS_REDEFINITION.FINISH_REDEF_TABLE()過程直接在重定義表上執行了大量的DML操作，那么可以選擇執行一次或多次的SYNC_INTERIM_TABLE()過程，此操作可以減少最后一步執行FINISH_REDEF_TABLE()過程時的鎖定時間。
--模擬業務不停，DML表數據寫入
insert into STUDENT values(25,'student_25','MALE',to_date('2020-8-1', 'yyyy-mm-dd'));
update student set s_sex='FEMALE' where s_id = 20;
commit;
--比對student和student_par數據
select s_id,s_name,s_sex,s_birdate from student
minus
select s_id,s_name,s_sex,s_birdate from student_par;
S_ID S_NAME S_SEX S_BIRDATE
---------- -------------------- -------- ------------------
20 student_20 FEMALE 01-SEP-20
25 student_25 MALE 01-AUG-20
--同步數據到臨時表
BEGIN
dbms_redefinition.sync_interim_table(
uname => 'PAR',
orig_table => 'STUDENT',
int_table => 'STUDENT_PAR');
END;
/
--數據已全部同步到臨時表
select s_id,s_name,s_sex,s_birdate from student
minus
select s_id,s_name,s_sex,s_birdate from student_par;
no rows selected
7.執行DBMS_REDEFINITION.FINISH_REDEF_TABLE
執行DBMS_REDEFINITION.FINISH_REDEF_TABLE()過程完成表的重定義。這個過程中，原始表會被獨占模式鎖定一小段時間，具體時間和表的數據量有關。
執行完FINISH_REDEF_TABLE()過程后，原始表重定義后具有了中間表的屬性、索引、約束、授權和觸發器。中間表上disabled的約束在原始表上處于enabled狀態。
--收集par table的統計信息
EXEC DBMS_STATS.gather_table_stats('PAR', 'STUDENT_PAR', cascade => TRUE);
--結束在線重定義過程
BEGIN
dbms_redefinition.finish_redef_table(
uname => 'PAR',
orig_table => 'STUDENT',
int_table => 'STUDENT_PAR');
END;
/
SQL> select table_name，PARTITION_NAME from user_tab_partitions where table_name in ('STUDENT','STUDENT_PAR');
SQL> select table_name,index_name from user_indexes where table_name in ('STUDENT','STUDENT_PAR');
此時，臨時表（及其索引）已成為“真實”表，并且它們的名稱已在名稱詞典中切換。
8.重命名所有約束和索引以匹配原始名稱
--drop中間表或者rename原來的約束
a.drop table STUDENT_PAR;
b.
ALTER TABLE STUDENT_PAR RENAME CONSTRAINT U_1 TO U_1_20210411;
ALTER TABLE STUDENT_PAR RENAME CONSTRAINT C_1 TO C_1_20210411;
ALTER INDEX S_NAME_IDX RENAME TO S_NAME_IDX_20210411;
ALTER INDEX U_1 RENAME TO U_1_20210411;
--rename 新分區表的約束和索引
ALTER TABLE STUDENT RENAME CONSTRAINT U_1_PAR TO U_1;
ALTER TABLE STUDENT RENAME CONSTRAINT C_1_PAR TO C_1;
ALTER INDEX S_NAME_IDX_PAR RENAME TO S_NAME_IDX;
ALTER INDEX U_1_PAR RENAME TO U_1;
--查看索引，約束名稱是否正確
select table_name,index_name from user_indexes where table_name in ('STUDENT','STUDENT_PAR') order by table_name;
TABLE_NAME INDEX_NAME
------------------------------ ------------------------------
STUDENT S_NAME_IDX
STUDENT SYS_C0011401
STUDENT U_1
STUDENT_PAR S_NAME_IDX_20210411
STUDENT_PAR U_1_20210411
STUDENT_PAR SYS_C0011395
SQL> desc stu
Name Null? Type
----------------------------------------- -------- ----------------------------
S_ID NOT NULL NUMBER(8)
S_NAME NOT NULL VARCHAR2(20)
S_SEX VARCHAR2(8)
S_BIRDATE DATE
S_PHONE NUMBER原文鏈接：https://juejin.cn/post/7029897089928658980
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