首先了解什麼是外部表，與其它表的區別，建立一個簡單的外部表（主要看操作過程），最後我們用外部表查看Oracle報警日志
一．了解Oracle外部表 外部表定義：結構被存放在數據字典，而表數據被放在OS文件中的表
作用：在數據庫中查詢OS文件的數據，還可以將OS文件數據裝載到數據庫中
與其它表的區別：在外部表上不能執行DML操作，也不能在外部表上建索引，只能執行select操用
二．建一個簡單的外部表 1．建一個OS上的文件
因為外部表主要是查看OS上的文件，首先在OS上建一個文件
mkdir -p /Oracle/ext
vi /Oracle/ext/ext.dat
10,20,30
40,50,60
70,80,90
2．授予用戶權限，並建立目錄對象
在此我們先建一個新用戶
create user test identifIEd by “123” default tablespace test quota unlimited on test;
用戶授權
SQL> grant create any directory to test;
建立目錄對象
SQL> conn test / 123
Connected.
SQL> create directory ext as '/Oracle/ext';
Directory created.
3.建立外部表
SQL> create table exttable(
id number,name varchar2(10),i number
)organization external
(type Oracle_loader
default directory ext
Access parameters
(records delimited by newline
fIElds terminated by ','
)location('ext.dat')
);
4.測試
SQL> select * from exttable;
ID NAME I
---------- ---------- ----------
10 20 30
40 50 60
70 80 90
測試成功,可見在數據庫中可以查詢OS文件的數據
二. 使用外部表查看Oracle報警日志 由於在上面實驗中已建立了一個用戶,並賦相應的權限,而且也有了OS文件(即報警文件alert_SID.log),所以在此直接建立目錄對象並建立外部表就可以了。
1．建立目錄對象
SQL> conn test / 123
Connected.
SQL> create directory bdump as '/oracle/u01/app/Oracle/admin/db2/bdump';
Directory created.
2．建立外部表
SQL> create table alert_log(
text varchar2(400)
)organization external
(type Oracle_loader
default directory bdump
Access parameters
(records delimited by newline
)location('alert_db2.log')
);
3．測試
首先查看能否查到alert_db2.log的內容
SQL> select * from alert_log where rownum < 10;
TEXT
Thu Jun 11 00:51:46 2009
Starting Oracle instance (normal)
Cannot determine all dependent dynamic librarIEs for /proc/self/exe
Unable to find dynamic library libocr10.so in search paths
RPATH = /ade/aime1_build2101/oracle/has/lib/:/ade/aime1_build2101/Oracle/lib/:/a
de/aime1_build2101/Oracle/has/lib/:
LD_LIBRARY_PATH is not set!
The default library directorIEs are /lib and /usr/lib
Unable to find dynamic library libocrb10.so in search paths
Unable to find dynamic library libocrutl10.so in search paths
9 rows selected.
測試成功
然後我們測試查報警信息’ORA-%’
SQL> select * from alert_log where text like 'ORA-%';
TEXT
ORA-00202: control file: '/oracle/u01/app/Oracle/product/10.2.0/db2/dbs/cntrldb2
.dbf'
ORA-27037: unable to obtain file status
ORA-205 signalled during: ALTER DATABASE MOUNT...
ORA-00301: error in adding log file '/home/oracle/Oracle/oradata/testdb/redo01.l
og' - file cannot be created
ORA-27040: file create error
ORA-1501 signalled during: CREATE DATABASE db2
ORA-00200: control file could not be created
TEXT
ORA-00202: control file: '/oracle/u01/app/Oracle/product/10.2.0/db2/dbs/cntrldb2
.dbf'
ORA-27038: created file already exists
ORA-1501 signalled during: CREATE DATABASE db2
ORA-00200: control file could not be created
ORA-00202: control file: '/oracle/u01/app/Oracle/product/10.2.0/db2/dbs/cntrldb2
.dbf'
ORA-27038: created file already exists
ORA-1501 signalled during: CREATE DATABASE db2
測試成功,
可見我們可以使用外部表來方便的查看Oracle的報警信息.
