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Oracle使用联机重定义来给表增加新列与分区

因为需要将一张上亿我们要记录的表修改为分区表,所以尝试使用联机重定义来给表增加新列与分区的方法来实现,下面是一个测试的例子,操作系统是Oracle Linux 7.1,数据库为12.2.0.1,原始表为emp_redef,该表存储在hr方案中:

SQL> desc hr.emp_redef
Name          Type         Nullable Default Comments
------------- ------------ -------- ------- --------
EMPLOYEE_ID   NUMBER(6)
FIRST_NAME    VARCHAR2(20) Y
LAST_NAME     VARCHAR2(25)
JOB_ID        VARCHAR2(10)
DEPARTMENT_ID NUMBER(4)    Y

表emp_redef将按以下规则来进行联机重定义:
.增加新列mgr,hiredate,sal与bonus
.新列bonus被初始化为0
.列department_id的值由10开始增加
.表将被重定义为范围分区表,分区键为employee_id。

联机重定义操作如下:
1.用要执行联机重定义操作的用户登录数据库

SQL> conn pm/pm@jypdb
Connected.

2.验证表emp_redef是否可以执行联机重定义。在这种情况下,可以使用主键或伪主键来来进行验证。

SQL> exec dbms_redefinition.can_redef_table(uname=>'HR',tname=>'EMP_REDEF',options_flag=>dbms_redefinition.cons_use_pk);

PL/SQL procedure successfully completed.

3.创建一个中间表hr.int_emp_redef

SQL> create table hr.int_emp_redef
  2  (
  3    employee_id   NUMBER(6) not null,
  4    first_name    VARCHAR2(20),
  5    last_name     VARCHAR2(25) not null,
  6    job_id        VARCHAR2(10) not null,
  7    department_id NUMBER(4) not null,
  8    mgr           NUMBER(5),
  9    hiredate      DATE DEFAULT(sysdate),
 10    sal           NUMBER(7,2),
 11    bonus         NUMBER(7,2) DEFAULT(0)
 12  )
 13  partition by range(employee_id)
 14  (
 15  partition emp200 values less than(200) tablespace users,
 16  partition emp400 values less than(400) tablespace users
 17  );
Table created

4.开始重定义操作

SQL> begin
  2  dbms_redefinition.start_redef_table(
  3    uname => 'hr',
  4    orig_table => 'emp_redef',
  5    int_table => 'int_emp_redef',
  6    col_mapping => 'employee_id employee_id, first_name first_name,last_name last_name, job_id job_id, department_id+10 department_id,0 bonus',
  7    options_flag => DBMS_REDEFINITION.CONS_USE_PK);
  8  end;
  9  /

PL/SQL procedure successfully completed.

5.复制依赖对象(自动对表hr.int_emp_redef创建任何触发器,索引,物化视图日志,授权与约束)

SQL> declare
  2  num_errors pls_integer;
  3  begin
  4  dbms_redefinition.copy_table_dependents(
  5    uname => 'hr',
  6    orig_table => 'emp_redef',
  7    int_table => 'int_emp_redef',
  8    copy_indexes => DBMS_REDEFINITION.CONS_ORIG_PARAMS,
  9    copy_triggers => TRUE,
 10    copy_constraints => TRUE,
 11    copy_privileges => TRUE,
 12    ignore_errors => TRUE,
 13    num_errors => num_errors);
 14  end;
 15  /

PL/SQL procedure successfully completed.

注意,在调用这个过程时ignore_errors参数需要设置为TRUE。原因是中间表创建了主键约束,并且当执行copye_table_dependents过程来试图从原始表复制主键约束与索引时会发生错误。可以忽略这些错误,但必须执行下一步操作中的查询来查看是否还存在其它错误。

6.查询dba_redefinition_errors视图来查看错误信息

SQL> set long 8000
SQL> set pages 8000
SQL> column object_name heading 'object name' format a20
SQL> column base_table_name heading 'base table name' format a10
SQL> column ddl_txt heading 'ddl that caused error' format a40
SQL> select object_name, base_table_name, ddl_txt from dba_redefinition_errors;

object name          base table ddl that caused error
-------------------- ---------- ----------------------------------------
SYS_C0023200         EMP_REDEF  ALTER TABLE "HR"."INT_EMP_REDEF" MODIFY
                                ("LAST_NAME" CONSTRAINT "TMP$$_SYS_C0023
                                2000" NOT NULL ENABLE NOVALIDATE)

SYS_C0023201         EMP_REDEF  ALTER TABLE "HR"."INT_EMP_REDEF" MODIFY
                                ("JOB_ID" CONSTRAINT "TMP$$_SYS_C0023201
                                0" NOT NULL ENABLE NOVALIDATE)


2 rows selected.

上面的错误信息是说中间表的last_name与job_id列为not null,而原因表为null,这种错误可以忽略。

7.同步中间表hr.int_emp_redef

SQL> begin
  2  dbms_redefinition.sync_interim_table(
  3    uname => 'hr',
  4    orig_table => 'emp_redef',
  5    int_table => 'int_emp_redef');
  6  end;
  7  /

PL/SQL procedure successfully completed.

8.完成重定义操作

SQL> begin
  2  dbms_redefinition.finish_redef_table(
  3   uname => 'hr',
  4   orig_table => 'emp_redef',
  5   int_table => 'int_emp_redef');
  6  end;
  7  /

PL/SQL procedure successfully completed.

表hr.emp_redef只会以排他模式被锁定很短的时间来结束重定义操作。在操作完成后,表hr.emp_redef将使用hr.int_emp_redef表的所有属性来重定义。

SQL> desc hr.emp_redef
Name          Type         Nullable Default   Comments
------------- ------------ -------- --------- --------
EMPLOYEE_ID   NUMBER(6)
FIRST_NAME    VARCHAR2(20) Y
LAST_NAME     VARCHAR2(25)
JOB_ID        VARCHAR2(10)
DEPARTMENT_ID NUMBER(4)
MGR           NUMBER(5)    Y
HIREDATE      DATE         Y        (sysdate)
SAL           NUMBER(7,2)  Y
BONUS         NUMBER(7,2)  Y        (0)

SQL> select dbms_metadata.get_ddl(object_type =>'TABLE',name =>'EMP_REDEF',schema => 'HR') from dual;

DBMS_METADATA.GET_DDL(OBJECT_TYPE=>'TABLE',NAME=>'EMP_REDEF',SCHEMA=>'HR')
--------------------------------------------------------------------------------

  CREATE TABLE "HR"."EMP_REDEF"
   (    "EMPLOYEE_ID" NUMBER(6,0) NOT NULL ENABLE,
        "FIRST_NAME" VARCHAR2(20),
        "LAST_NAME" VARCHAR2(25) NOT NULL ENABLE,
        "JOB_ID" VARCHAR2(10) NOT NULL ENABLE,
        "DEPARTMENT_ID" NUMBER(4,0) NOT NULL ENABLE,
        "MGR" NUMBER(5,0),
        "HIREDATE" DATE DEFAULT (sysdate),
        "SAL" NUMBER(7,2),
        "BONUS" NUMBER(7,2) DEFAULT (0),
         CONSTRAINT "EMP_REDEF_EMP_ID_PK" PRIMARY KEY ("EMPLOYEE_ID")
  USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "USERS"  ENABLE
   ) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255
  STORAGE(
  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "USERS"
  PARTITION BY RANGE ("EMPLOYEE_ID")
 (PARTITION "EMP200"  VALUES LESS THAN (200) SEGMENT CREATION IMMEDIATE
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255
 NOCOMPRESS LOGGING
  STORAGE(INITIAL 8388608 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "USERS" ,
 PARTITION "EMP400"  VALUES LESS THAN (400) SEGMENT CREATION IMMEDIATE
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255
 NOCOMPRESS LOGGING
  STORAGE(INITIAL 8388608 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "USERS" )


1 row selected.

可以看到表hr.emp_redef已经成功能联机重定义

9.等任何查询中间表的语句执行完成后将其删除,而且中间表在重定义后其结构就变成了原始表的表结构

SQL> desc hr.int_emp_redef
Name          Type         Nullable Default Comments
------------- ------------ -------- ------- --------
EMPLOYEE_ID   NUMBER(6)    Y
FIRST_NAME    VARCHAR2(20) Y
LAST_NAME     VARCHAR2(25)
JOB_ID        VARCHAR2(10)
DEPARTMENT_ID NUMBER(4)    Y

SQL> drop table hr.int_emp_redef purge;
Table dropped

到此,联机重定义表hr.emp_redef就操作完成。

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