Oracle数据加载之外部表的介绍

环境:
服务端:RHEL6.4 + Oracle 11.2.0.4
目录:
一、 创建外部表

• 1.1 创建外部表需要的目录
• 1.2 创建外部表
• 1.3 创建外部表源文件
• 1.4 查询外部表

二、 加载外部表数据到普通表

• 2.1 创建普通表
• 2.2 直接插入
• 2.3 直接路径插入

三、References

一、 创建外部表

1.1 创建外部表需要的目录

``` create or replace directory admin as '/u01/jingyu'; ```

1.2 创建外部表

``` drop table dept_external purge; CREATE TABLE dept_external ( deptno NUMBER(6), dname VARCHAR2(20), loc VARCHAR2(25) ) ORGANIZATION EXTERNAL (TYPE oracle_loader DEFAULT DIRECTORY admin ACCESS PARAMETERS ( RECORDS DELIMITED BY newline BADFILE 'ulcase1.bad' DISCARDFILE 'ulcase1.dis' LOGFILE 'ulcase1.log' SKIP 10 FIELDS TERMINATED BY "," OPTIONALLY ENCLOSED BY '"' ( deptno INTEGER EXTERNAL(6), dname CHAR(20), loc CHAR(25) ) ) LOCATION ('ulcase1.ctl') ) REJECT LIMIT UNLIMITED; ```

1.3 创建外部表源文件

创建源文件ulcase1.ctl ``` LOAD DATA INFILE * BADFILE 'sample.bad' DISCARDFILE 'sample.dsc' APPEND INTO TABLE emp WHEN (57) = '.' TRAILING NULLCOLS (deptno, dname, loc) BEGINDATA 10,ACCOUNTING,NEW YORK 20,RESEARCH,DALLAS 30,SALES,CHICAGO 40,OPERATIONS,BOSTON ``` 这里是把这个ctl文件当作数据文件使用,上面skip=10对应了是跳过前面10行无效信息,从数据行开始读取。

1.4 查询外部表

``` SQL> select * from dept_external;

DEPTNO DNAME                LOC

---

    10 ACCOUNTING           NEW YORK
    20 RESEARCH             DALLAS
    30 SALES                CHICAGO
    40 OPERATIONS           BOSTON

<h1 id="2">二、 加载外部表数据到普通表</h1>
<h2 id="2.1">2.1 创建普通表</h2>

CREATE TABLE dept (
deptno NUMBER(6),
dname VARCHAR2(20),
loc VARCHAR2(25)
) tablespace dbs_d_jingyu;

<h2 id="2.2">2.2 直接插入</h2>

insert into dept select * from dept_external;
commit;

<h2 id="2.3">2.3 直接路径插入</h2>

insert /+append/ into dept select * from dept_external;
commit;

一般情况,直接路径插入的效率要高。因为:
> 1. Data is appended to the end of the table, rather than attempting to use existing free space within the table.
> 2. Data is written directly to the data files, by-passing the buffer cache.
> 3. Referential integrity constraints are not considered. *
> 4. No trigger processing is performed. *

<h1 id="3">三、References</h1>

- "APPEND Hint".[Online]  Available: 
[https://oracle-base.com/articles/misc/append-hint](https://oracle-base.com/articles/misc/append-hint) (Sep 23,2015)
- Oracle® Database SQL Language Reference 11g Release 2 (11.2)