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)