生产环境中考虑到数据库的性能问题，很少会打开数据的审计功能，应用层也不会记录SQL的执行信息；但是生产上经常会遇到某张表的某几条被修改掉，但是应用又查不到是哪个接口修改的记录，这时候Logminer 就派上用场了。

Logminer 8i之后的一款免费日志分析工具：通过分析在线日志文件或者归档日志文件，返回数据库DDL/DML操作语句、执行时间、用户等等可以追查的信息，快速定位问题。

使用Logminer 工具，数据库需要开启强制日志和归档模式

数据库配置

# 开启强制日志模式# 查看当前数据库日志模式SQL> SELECT supplemental_log_data_min, force_logging FROM v$database;# 如果返回结果为NO，则SQL> ALTER DATABASE ADD SUPPLEMENTAL LOG DATA;SQL> ALTER DATABASE FORCE LOGGING;# 确认是否已经修改，输出为YESSQL> SELECT supplemental_log_data_min, force_logging FROM v$database;# 切换系统日志SQL> ALTER SYSTEM SWITCH LOGFILE;# 数据库处于归档模式SQL> archive log listDatabase log mode           Archive ModeAutomatic archival           EnabledArchive destination           USE_DB_RECOVERY_FILE_DESTOldest online log sequence     107Next log sequence to archive   109Current log sequence           109# 默认归档日志路径SQL> show parameter db_recoverNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------db_recovery_file_dest             string     /u01/app/oracle/fast_recovery_areadb_recovery_file_dest_size         big integer 4977M# 若数据库处于非归档模式，则需要# 干净的关闭掉数据库SQL> shutdown immediate# 打开至mount状态SQL> startup mount# 设置为归档模式SQL> alter database archivelog;# 开启数据库SQL> alter database open;

Logminer 配置

# 首先安装 logminer 使用到的包，将创建用于分析的过程和视图SQL> @$ORACLE_HOME/rdbms/admin/dbmslm.sqlSQL> @$ORACLE_HOME/rdbms/admin/dbmslmd.sql# 参数配置，用于创建字典文件SQL> show parameter utlNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------utl_file_dir                 string     /u01/app/oracle/logminer# 如果VALUE 为 NULL，那么需要在线修改并重启实例生效SQL> alter system set utl_file_dir='/u01/app/oracle/logminer' scope=spfile;#  创建字典文件SQL> CREATE DIRECTORY utlfile AS '/u01/app/oracle/logminer';SQL> EXECUTE dbms_logmnr_d.build(dictionary_filename => 'dictionary.ora', dictionary_location =>'/u01/app/oracle/logminer');SQL> !ls  /u01/app/oracle/logminerdictionary.ora

对测试数据表进行操作

#  创建临时表SQL>  create table u_logminer.dba_objects as select * from all_objects;# 更新操作SQL> select status,owner,object_name from U_LOGMINER.dba_objects where owner = 'U_LOGMINER';STATUS    OWNER                   OBJECT_NAME------- ------------------------------ --------------------INVALID U_LOGMINER               ALL_OBJECTSINVALID U_LOGMINER               ALL_OBJECTSINVALID U_LOGMINER               ALL_OBJECTSINVALID U_LOGMINER               ALL_OBJECTS # update 更新SQL> update U_LOGMINER.dba_objects set STATUS = 'VALID' where owner = 'U_LOGMINER';4 rows updated.SQL> commit;Commit complete.SQL> select status,owner,object_name from U_LOGMINER.dba_objects where owner = 'U_LOGMINER';STATUS    OWNER                   OBJECT_NAME------- ------------------------------ --------------------VALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTS# insert 插入SQL> insert into U_LOGMINER.dba_objects select * from dba_objects where owner = 'U_LOGMINER';4 rows created.SQL> commit;Commit complete.SQL> select status,owner,object_name from U_LOGMINER.dba_objects where owner = 'U_LOGMINER';STATUS    OWNER                   OBJECT_NAME------- ------------------------------ --------------------VALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTSVALID    U_LOGMINER               ALL_OBJECTS8 rows selected.# delete 删除SQL> delete from U_LOGMINER.dba_objects where owner = 'U_LOGMINER';8 rows deleted.SQL> commit;Commit complete.

使用Logminer 分析归档日志

# 添加日志文件进行分析，第一个文件 dbms_logmnr.NEW，后面的文件dbms_logmnr.ADDFILESQL> BEGIN  2  dbms_logmnr.add_logfile(logfilename=>'/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2017_08_19/o1_mf_1_106_dshlmn6r_.arc',options=>dbms_logmnr.NEW);  3  dbms_logmnr.add_logfile(logfilename=>'/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2017_08_19/o1_mf_1_107_dshlmoo2_.arc',options=>dbms_logmnr.ADDFILE);  4  dbms_logmnr.add_logfile(logfilename=>'/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2017_08_19/o1_mf_1_108_dshm5n1x_.arc',options=>dbms_logmnr.ADDFILE);  5  end;  6  /PL/SQL procedure successfully completed.# 开始分析，当前是完整分析日志文件的内容，可以操作时间、SCN等过滤需要分析的内容SQL> EXECUTE dbms_logmnr.start_logmnr(dictfilename =>'/u01/app/oracle/logminer/dictionary.ora');# 或者SQL> EXECUTE dbms_logmnr.start_logmnr(DictFileName =>'/u01/app/oracle/logminer/dictionary.ora', StartTime =>to_date('2017-8-19 00:00:00','YYYY-MM-DD HH24:MI:SS'),EndTime =>to_date('2017-8-19 17:00:00','YYYY-MM-DD HH24:MI:SS '));# 或者SQL> SQL> EXECUTE dbms_logmnr.start_logmnr(DictFileName =>'/u01/app/oracle/logminer/dictionary.ora', StartScn>=20, EndScn<= 50);PL/SQL procedure successfully completed.# 结果放在视图中，注意当会话结束，临时表会被删除SQL> SELECT count(*) FROM v$logmnr_contents;   COUNT(*)----------     42118# 将临时表数据备份至物理表中SQL> create table u_logMIner.logminer_tmp as select * from  v$logmnr_contents; Table created.

日志文件分析完成，接下来就看看对表到底做了什么操作

# 根据事务开始时间进行排序，查询数据表的变更记录SQL > SELECT START_TIMESTAMP,COMMIT_TIMESTAMP,sql_redo,sql_undo,machine_name,os_username,username,table_name FROM u_logMIner.logminer_tmp WHERE username='U_LOGMINER' AND table_name='DBA_OBJECTS' order by START_TIMESTAMP;# sql_redo 更改数据的SQL# sql_undo 回滚数据的SQL# machine_name,os_username,username 三位一体定位执行更新的机器、数据库用户名# 如下：SQL> SELECT sql_redo FROM u_logMIner.logminer_tmp WHERE username='U_LOGMINER' AND table_name='DBA_OBJECTS' order by START_TIMESTAMP;SQL_REDO--------------------------------------------------------------------------------update "U_LOGMINER"."DBA_OBJECTS" set "STATUS" = 'INVALID' where "STATUS" = 'VALID' and ROWID = 'AAAD8EAAIAAAAJAAAf';update "U_LOGMINER"."DBA_OBJECTS" set "STATUS" = 'INVALID' where "STATUS" = 'VALID' and ROWID = 'AAAD8EAAIAAAAKHAAv';…………# 如下：SQL> SELECT sql_undo FROM u_logMIner.logminer_tmp WHERE username='U_LOGMINER' AND table_name='DBA_OBJECTS' order by START_TIMESTAMP;SQL_UNDO--------------------------------------------------------------------------------update "U_LOGMINER"."DBA_OBJECTS" set "STATUS" = 'VALID' where "STATUS" = 'INVALID' and ROWID = 'AAAD8EAAIAAAAJAAAf';update "U_LOGMINER"."DBA_OBJECTS" set "STATUS" = 'VALID' where "STATUS" = 'INVALID' and ROWID = 'AAAD8EAAIAAAAKHAAv';update "U_LOGMINER"."DBA_OBJECTS" set "STATUS" = 'VALID' where "STATUS" = 'INVALID' and ROWID = 'AAAD8EAAIAAAAPoAA0';………………

SQL拿出来了，就可以定位问题，但是能不能立刻回滚到生产环境，还需要和业务部门进行沟通。

建议在创建数据库时，就打开强制日志、归档模式，配置 utl_file_dir 参数，避免数据库重启对线上的影像

当然也可以直接下其他环境下的数据库做日志分析工作，有两个点需要注意：数据字典和日志文件，其他和在本机处理没什么两样。