在网上查了几天的资料，尝试综合清除告警日志内容及建外部表的方式来解决这一问题。
一：备份并清除告警日志内容
将每天的告警日志备份好，然后进行清除。
1:备份报警日志
在$ORACLE_HOME/SID/bdump/ 目录下，
按日期备份alert_ORACLE_你的实例名.LOG这个文件,如：alert_ORACLE_orcl_201408111639_bak.LOG。
2:清除日志内容
打开报警日志文件，用true > 文件名 可清除掉里面的内容
具体示例：
假如，我现在第一次进行该设置，我先把现有的告警日志进行备份，如：
-清空报警日志
alert_orcl2.log
现在告警日志是空的。
切换下归档日志，检查报警日志里是否出现了新内容：
alter system switch logfile;
System altered.
则现在alert_orcl2.log记录的是2014年8月11日16点24分后至你下次对报警日志进行备份，截取前的信息。
二：建外部表查看报警日志错误
如果已建立了一个用户,并赋相应的权限，所以直接建立目录对象并建立外部表就可以了。
1．建立目录对象
conn test / 123
Connected. sql> create directory bdump as '/oracle/u01/app/oracle/admin/db2/bdump'; Directory created.
Connected. sql> create directory bdump as '/oracle/u01/app/oracle/admin/db2/bdump'; Directory created.
2．建立外部表
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．测试首先查看能否查到alert_db2.log的内容
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.
测试成功
然后我们测试查报警信息'ORA-%'
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
--假如，你的报警日志文件只包含今天的信息（可以通过备份并清除告警日志内容实现），则通过外部表可以查到当天产生了哪些错误。
