怎样使用log miner分析oracle日志

时间:2020-12-17 Kevin_ora 人气:0

日常生活中，我们经常因为操作失误丢失数据或者是更改数据，如何进行恢复呐？这篇文章就是帮助我们解决这一困扰,需要的朋友可以参考下

当我们不小心误操作致使数据库数据丢失、改变时，需要对数据库对象做基于时间点的恢复，找到我们需要的数据，这个时间点不能认为精确确定，我们可以通过对oracle日志进行分析，而获得无操作的精确时间点。
oracle db提供了一个分析日志包logmnr
logminer 工具的使用
-------对redo log 进行挖掘，找出在某个时间点所作的DDL 或DML 操作（包括：时间点、datablock scn 、sql语句）
实验测试

SQL> select name from v$archived_log;
 
NAME
--------------------------------------------------
/oracle/arch1/1_2_883536782.dbf
 
SQL>
SQL>
SQL> delete from scott.t1; 
576 rows deleted. 
SQL> alter system archive log current; 
System altered. 
SQL> create table scott.t6 as select * from scott.emp; 
Table created. 
SQL> alter system archive log current;
System altered.
SQL> select name from v$archived_log;
 
NAME
--------------------------------------------------
/oracle/arch1/1_2_883536782.dbf
/oracle/arch1/1_3_883536782.dbf
/oracle/arch1/1_4_883536782.dbf

--启动log miner添加要分析的日志

SQL> execute dbms_logmnr.add_logfile(logfilename=>'/oracle/arch1/1_2_883536782.dbf',options=>dbms_logmnr.new);

PL/SQL procedure successfully completed.

--添加需要分析的日志

SQL> execute dbms_logmnr.add_logfile(logfilename=>'/oracle/arch1/1_3_883536782.dbf',options=>dbms_logmnr.addfile); 

PL/SQL procedure successfully completed. 

SQL> execute dbms_logmnr.add_logfile(logfilename=>'/oracle/arch1/1_4_883536782.dbf',options=>dbms_logmnr.addfile) 

PL/SQL procedure successfully completed.

--执行log miner


SQL> execute dbms_logmnr.start_logmnr(options=>dbms_logmnr.dict_from_online_catalog); 

PL/SQL procedure successfully completed.

--查询分析结果

SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss'; 
Session altered.
SQL> select username,scn,timestamp,sql_redo from v$logmnr_contents where seg_name='T1'; 
USERNAME  SCN TIMESTAMP
------------------------------ ---------- -------------------
SQL_REDO
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
delete from "SCOTT"."T1" where "EMPNO" = '7782' and "ENAME" = 'CLARK' and "JOB" = 'MANAGER' and "MGR" = '7839' and "HIREDATE" = TO_DATE('1981-06-09 00:00:00', 'yyyy-mm-dd hh24:mi:ss') and "SAL" = '245
0' and "COMM" IS NULL and "DEPTNO" = '10' and ROWID = 'AAAVbSAAFAAAACXABi';
 
SYS  1494545 2015-06-28 04:24:44
delete from "SCOTT"."T1" where "EMPNO" = '7839' and "ENAME" = 'KING' and "JOB" = 'PRESIDENT' and "MGR" IS NULL and "HIREDATE" = TO_DATE('1981-11-17 00:00:00', 'yyyy-mm-dd hh24:mi:ss') and "SAL" = '500
0' and "COMM" IS NULL and "DEPTNO" = '10' and ROWID = 'AAAVbSAAFAAAACXABj';
 
SYS  1494545 2015-06-28 04:24:44
delete from "SCOTT"."T1" where "EMPNO" = '7844' and "ENAME" = 'TURNER' and "JOB" = 'SALESMAN' and "MGR" = '7698' and "HIREDATE" = TO_DATE('1981-09-08 00:00:00', 'yyyy-mm-dd hh24:mi:ss') and "SAL" = '1
。。。。。

--结束log miner 分析

SQL> execute dbms_logmnr.end_logmnr;
 
PL/SQL procedure successfully completed.

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