oracle_外部表的两种实现方式oracle_loader[datapump]

外部表可以实现，通过数据库对象直接访问目录文件里的格式数据，加载方式分为两种oracle_loader和oracle_datapump,oracle_loader方式通过sqlldr引擎方式加载，访问flat格式文件；oracle_datapump通过datapump接口来加载，访问通过oracle_datapump方式卸载的dmp文件；

 

 

 

 

------oracle_loader

----自定义两个格式文件内容如下：

====a.dat====

360,Jane,Janus,ST_CLERK,121,17-MAY-2001,3000,0,50,jjanus

361,Mark,Jasper,SA_REP,145,17-MAY-2001,8000,.1,80,mjasper

362,Brenda,Starr,AD_ASST,200,17-MAY-2001,5500,0,10,bstarr

363,Alex,Alda,AC_MGR,145,17-MAY-2001,9000,.15,80,aalda

 

====b.dat====

401,Jesse,Cromwell,HR_REP,203,17-MAY-2001,7000,0,40,jcromwel

402,Abby,Applegate,IT_PROG,103,17-MAY-2001,9000,.2,60,aapplega

403,Carol,Cousins,AD_VP,100,17-MAY-2001,27000,.3,90,ccousins

404,John,Richardson,AC_ACCOUNT,205,17-MAY-2001,5000,0,110,jrichard

 

 

----创建需要的目录

CONNECT  /  AS SYSDBA;

-- Set up directories and grant access to hr 

CREATE OR REPLACE DIRECTORY admin_dat_dir

    AS '/u01/backup'; 

CREATE OR REPLACE DIRECTORY admin_log_dir 

    AS '/u01/backup'; 

CREATE OR REPLACE DIRECTORY admin_bad_dir 

    AS '/u01/backup'; 

GRANT READ ON DIRECTORY admin_dat_dir TO sun; 

GRANT WRITE ON DIRECTORY admin_log_dir TO sun; 

GRANT WRITE ON DIRECTORY admin_bad_dir TO sun;

 

----通过loader方式创建外部表，直接通过表来查询操作

conn sun/sun

-- create the external table

CREATE TABLE admin_ext_employees

                   (employee_id       NUMBER(4), 

                    first_name        VARCHAR2(20),

                    last_name         VARCHAR2(25), 

                    job_id            VARCHAR2(10),

                    manager_id        NUMBER(4),

                    hire_date         DATE,

                    salary            NUMBER(8,2),

                    commission_pct    NUMBER(2,2),

                    department_id     NUMBER(4),

                    email             VARCHAR2(25) 

                   ) 

     ORGANIZATION EXTERNAL 

     ( 

       TYPE ORACLE_LOADER 

       DEFAULT DIRECTORY admin_dat_dir 

       ACCESS PARAMETERS 

       ( 

         records delimited by newline 

         badfile admin_bad_dir:'empxt%a_%p.bad' 

         logfile admin_log_dir:'empxt%a_%p.log' 

         fields terminated by ',' 

         missing field values are null 

         ( employee_id, first_name, last_name, job_id, manager_id, 

           hire_date char date_format date mask "dd-mon-yyyy", 

           salary, commission_pct, department_id, email 

         ) 

       ) 

       LOCATION ('a.dat', 'b.dat') 

     ) 

     PARALLEL 

     REJECT LIMIT UNLIMITED; 

     

create table emp as select * from admin_ext_employees;     

 

 

SQL> 

SQL> SELECT * FROM emp;

 

EMPLOYEE_ID FIRST_NAME           LAST_NAME                 JOB_ID     M

----------- -------------------- ------------------------- ---------- -

        401 Jesse                Cromwell                  HR_REP      

        402 Abby                 Applegate                 IT_PROG     

        403 Carol                Cousins                   AD_VP       

        404 John                 Richardson                AC_ACCOUNT  

        360 Jane                 Janus                     ST_CLERK    

        361 Mark                 Jasper                    SA_REP      

        362 Brenda               Starr                     AD_ASST     

        363 Alex                 Alda                      AC_MGR      

SQL> SELECT * FROM user_external_tables ;

 

no rows selected

 

 

[ora11@prim backup]$ ls -l

total 20

-rw-r--r-- 1 ora11 oinstall  228 Sep  6 21:17 a.dat

-rw-r--r-- 1 ora11 oinstall  252 Sep  6 21:17 b.dat

-rw-r--r-- 1 ora11 oinstall 2826 Sep  6 21:19 empxt000_2756.log

-rw-r--r-- 1 ora11 oinstall 3110 Sep  6 21:19 empxt000_2763.log

-rw-r--r-- 1 ora11 oinstall 3110 Sep  6 21:19 empxt001_2765.log

 

 

------oracle_datapump

----更多是实现数据迁移的功能，通过datapump方式卸载并迁移到其他系统；

----创建datapump方式的外部表，并将数据卸载到目录文件中；

SQL> CREATE TABLE admin_ext_employees

  2                     (employee_id     ,

  3                      first_name      ,

  4                      last_name       , 

  5                      job_id          ,

  6                      manager_id      ,

  7                      hire_date       ,

  8                      salary          ,

  9                      commission_pct  ,

 10                      department_id   ,

 11                      email           

 12                     ) 

 13       ORGANIZATION EXTERNAL 

 14       ( 

 15         TYPE ORACLE_DATAPUMP 

 16         DEFAULT DIRECTORY admin_dat_dir 

 17         LOCATION ('emp2.dmp'))

 18        AS SELECT  * FROM emp;

 

Table created.

 

----查询文件内容，大体是产生XML格式的文件

-rw-r----- 1 ora11 oinstall 12288 Sep  6 21:33 emp2.dmp

[ora11@prim backup]$ strings emp2.dmp 

"SUN"."U"

x86_64/Linux 2.4.xx

 

 

----通过loader方式创建外部表，直接通过表来查询操作

SQL> CREATE TABLE admin_ext_employees2

  2                     (employee_id       NUMBER(4), 

  3                      first_name        VARCHAR2(20),

  4                      last_name         VARCHAR2(25), 

  5                      job_id            VARCHAR2(10),

  6                      manager_id        NUMBER(4),

  7                      hire_date         DATE,

  8                      salary            NUMBER(8,2),

  9                      commission_pct    NUMBER(2,2),

 10                      department_id     NUMBER(4),

 11                      email             VARCHAR2(25) 

 12                     ) 

 13       ORGANIZATION EXTERNAL 

 14       ( 

 15         TYPE ORACLE_DATAPUMP 

 16         DEFAULT DIRECTORY admin_dat_dir 

 17         LOCATION ('emp2.dmp')) ;

 

Table created.

 

SQL> 

SQL> SELECT * FROM admin_ext_employees2 ;

 

EMPLOYEE_ID FIRST_NAME           LAST_NAME                 JOB_ID    

----------- -------------------- ------------------------- ----------

        401 Jesse                Cromwell                  HR_REP    

        402 Abby                 Applegate                 IT_PROG   

        403 Carol                Cousins                   AD_VP     

        404 John                 Richardson                AC_ACCOUNT

        360 Jane                 Janus                     ST_CLERK  

        361 Mark                 Jasper                    SA_REP    

        362 Brenda               Starr                     AD_ASST   

        363 Alex                 Alda                      AC_MGR