Oracle 数据库审计功能非常强大，通常包括标准审计(包括用户级审计和系统级审计)和细粒度审计。尽管如此，一不小心就容易造成性能问题。同时会把系统表空间给撑爆。下面的内容描述的是如何将审计从系统表空间剥离以及清理Oracle审计记录，供大家参考。

一、审计的相关配置

--环境SQL> select * from v$version where rownum=1;BANNER--------------------------------------------------------------------------------Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit ProductionSQL> show parameter auditNAME                                 TYPE        VALUE------------------------------------ ----------- ------------------------------audit_file_dest                      string      /home/oraprod/app/product/11.2                                                 .0/dbhome_1/rdbms/auditaudit_sys_operations                 boolean     FALSEaudit_syslog_level                   stringaudit_trail                          string      DB  --此值为当前Oracle 11gR2缺省配置--从下面的查询中可以看出，当前的审计位于system表空间SQL> col segment_name FOR a10SQL> SELECT owner,segment_name,tablespace_name FROM dba_segments WHERE segment_name ='AUD$';OWNER                          SEGMENT_NA TABLESPACE_NAME------------------------------ ---------- ------------------------------SYS                            AUD$       SYSTEM

二、修改审计存储表空间

新增一个表空间用于存储审计日志SQL> CREATE tablespace audit_data datafile '/home/oracle/app/oradata/orcl/audit01.dbf'  2  SIZE 100M autoextend ON NEXT 50M;SQL> @tbs_free.sqlTABLESPACE_NAME                USED (MB FREE (MB TOTAL (M PER_FR------------------------------ -------- -------- -------- ------AUDIT_DATA                            1    1,199    1,200  100 %SYSAUX                            1,133       77    1,210    6 %SYSTEM                            1,875       15    1,890    1 %-- 设定审计数据存放表空间  SQL> BEGIN  2    DBMS_AUDIT_MGMT.SET_AUDIT_TRAIL_LOCATION(  3      AUDIT_TRAIL_TYPE => DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD,  4      AUDIT_TRAIL_LOCATION_VALUE => 'AUDIT_DATA'  5    );  6  END;  7  /BEGIN*ERROR at line 1:ORA-46267: Insufficient space in 'AUDIT_DATA' tablespace, cannot completeoperationORA-06512: at "SYS.DBMS_AUDIT_MGMT", line 1576ORA-06512: at line 2-- 错误提示，尽管我们使用了自动扩展表空间，依旧提示空间不够-- 查看当前审计数据大小，如下为1152MBSQL> select segment_name,bytes/1024/1024 from dba_segments where segment_name='AUD$';SEGMENT_NAME              BYTES/1024/1024------------------------- ---------------AUD$                                 1152-- 下面调整数据文件大小SQL> alter database datafile '/home/oracle/app/oradata/orcl/audit01.dbf' resize 1200m;Database altered.-- 再次设定审计数据存放表空间OK SQL> BEGIN  2    DBMS_AUDIT_MGMT.SET_AUDIT_TRAIL_LOCATION(  3      AUDIT_TRAIL_TYPE => DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD,  4      AUDIT_TRAIL_LOCATION_VALUE => 'AUDIT_DATA'  5    );  6  END;  7  /PL/SQL procedure successfully completed.Elapsed: 00:02:23.10--整个过程花费了2m23s，主要是期间进行了数据搬迁SQL> SELECT owner,segment_name,tablespace_name FROM dba_segments WHERE segment_name ='AUD$';OWNER                          SEGMENT_NAME                   TABLESPACE_NAME------------------------------ ------------------------------ ------------------------------SYS                            AUD$                           AUDIT_DATASQL> @tbs_free.sqlTABLESPACE_NAME                USED (MB FREE (MB TOTAL (M PER_FR------------------------------ -------- -------- -------- ------AUDIT_DATA                        1,153       47    1,200    4 %SYSAUX                            1,143       67    1,210    6 %SYSTEM                              724    1,166    1,890   62 %-- 从上面的这个查询可以看出，原来位于system表空间的AUD$被迁移到了AUDIT_DATA-- 相应地AUDIT_DATA表空间已使用增加，而SYSTEM表空间使用率下降-- 查看审计数据字典配置信息SQL> col PARAMETER_NAME FOR a30SQL> col PARAMETER_VALUE FOR a15SQL> col AUDIT_TRAIL FOR a20SQL> SELECT PARAMETER_NAME, PARAMETER_VALUE, AUDIT_TRAIL  2  FROM DBA_AUDIT_MGMT_CONFIG_PARAMS  3  WHERE audit_trail = 'STANDARD AUDIT TRAIL';PARAMETER_NAME                 PARAMETER_VALUE AUDIT_TRAIL------------------------------ --------------- --------------------DB AUDIT TABLESPACE            AUDIT_DATA      STANDARD AUDIT TRAILDB AUDIT CLEAN BATCH SIZE      10000           STANDARD AUDIT TRAIL

三、清除审计记录

通过这个过程设定清除间隔SQL> BEGIN  2    DBMS_AUDIT_MGMT.init_cleanup(  3      audit_trail_type         => DBMS_AUDIT_MGMT.AUDIT_TRAIL_ALL,  4      default_cleanup_interval => 120 /* hours */);  5  END;  6  /PL/SQL procedure successfully completed.-- 下面严验证审计日志清除是否已开启SQL> SET SERVEROUTPUT ONSQL> BEGIN  2    IF DBMS_AUDIT_MGMT.is_cleanup_initialized(DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD) THEN  3      DBMS_OUTPUT.put_line('YES');  4    ELSE  5      DBMS_OUTPUT.put_line('NO');  6    END IF;  7  END;  8  /YESPL/SQL procedure successfully completed.SQL> select segment_name,bytes/1024/1024 from dba_segments where segment_name='AUD$';SEGMENT_NAME        BYTES/1024/1024------------------- ---------------AUD$                           1152SQL> select 'Leshami' As author,'http://blog.csdn.net/leshami' as Blog from dual;AUTHOR  BLOG------- ----------------------------Leshami http://blog.csdn.net/leshamiSQL> select count(*) from AUD$;  COUNT(*)----------   5908086SQL> select min(ntimestamp#) from aud$;MIN(NTIMESTAMP#)---------------------------------------------------------------------------20-AUG-14 06.11.09.901253 AM-- 设定归档间隔SQL> BEGIN  2  DBMS_AUDIT_MGMT.set_last_archive_timestamp(  3  audit_trail_type  => DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD,  4  last_archive_time => SYSTIMESTAMP-10);  5  END;  6  /PL/SQL procedure successfully completed--查看设定的归档间隔SQL> SELECT * FROM dba_audit_mgmt_last_arch_ts;AUDIT_TRAIL          RAC_INSTANCE LAST_ARCHIVE_TS-------------------- ------------ ---------------------------------------------------------------------------STANDARD AUDIT TRAIL            0 09-OCT-15 01.27.17.000000 PM +00:00--通过调用DBMS_AUDIT_MGMT.clean_audit_trail进行手动清理审计日志BEGIN  DBMS_AUDIT_MGMT.clean_audit_trail(   audit_trail_type        => DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD,   use_last_arch_timestamp => TRUE);END;/DBMS_AUDIT_MGMT.clean_audit_trailThis procedure deletes audit trail records. The CLEAN_AUDIT_TRAIL procedure is usually called after the SET_LAST_ARCHIVE_TIMESTAMP Procedure has been used to set the last archived timestamp for the audit records.--也可以通过创建一个purge Job来进行清理已归档的历史审计记录SQL> BEGIN  2    DBMS_AUDIT_MGMT.CREATE_PURGE_JOB(  3      AUDIT_TRAIL_TYPE           => DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD,  4      AUDIT_TRAIL_PURGE_INTERVAL => 24 /* hours */,  5      AUDIT_TRAIL_PURGE_NAME     => 'Daily_Audit_Purge_Job',  6      USE_LAST_ARCH_TIMESTAMP    => TRUE  7    );  8  END;  9  /PL/SQL procedure successfully completed.-- 本次测试使用了job进行清理，注，上面的purge job 并非使用DBMS_SCHEDULER.CREATE_JOB创建-- 执行job用于清理归档，通过观察，由于redo log size为50MB，切换较为频繁，花费了19分钟-- 同时伴随有Checkpoint not complete等待事件，可见redo size过小SQL> exec DBMS_SCHEDULER.RUN_JOB(job_name => 'SYS.DAILY_AUDIT_PURGE_JOB');PL/SQL procedure successfully completed.Elapsed: 00:19:26.38SQL> select count(*) from AUD$;  COUNT(*)----------        12--经查看，清理后空间并没有释放        SQL> select segment_name,bytes/1024/1024 from dba_segments where segment_name='AUD$';SEGMENT_NAME                   BYTES/1024/1024------------------------------ ---------------AUD$                                      1152SQL> alter table sys.aud$ shrink space cascade;alter table sys.aud$ shrink space cascade*ERROR at line 1:ORA-10636: ROW MOVEMENT is not enabledSQL> alter table sys.aud$ enable row movement;Table altered.SQL> alter table sys.aud$ shrink space cascade;Table altered.SQL> alter table sys.aud$ disable row movement;Table altered.-- 下面的查询可以看到，空间已经被释放SQL> select segment_name,bytes/1024/1024 from dba_segments where segment_name='AUD$';SEGMENT_NAME         BYTES/1024/1024-------------------- ---------------AUD$                           .0625

四、小结

a、对于Oracle 11g，审计功能默认被开启，因此如果在必须启用的情况下应考虑性能影响；

b、开启审计的情况下，建议将审计从system或sysaux表空间剥离，使用单独的表空间； c、对于历史审计日志的清除，应考虑清除期间所带来的性能影响； d、调用DBMS_AUDIT_MGMT.SET_AUDIT_TRAIL_LOCATION这个过程已经开始了搬迁过程，如果审计日志很庞大，应考虑IO影响； e、审计日志的清除需要先设定归档，已归档的审计日志会被清理; f、也可以通过trunate table aud$ reuse storage以及deallocate非常规方式来处理。