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标题:ORA-01052: required destination LOG_ARCHIVE_DUPLEX_DEST is not specified
作者:惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]
SCN说明
1、Oracle的SCN在每秒16384次commit的情况下可以维持534年,每秒16384次commit是Oracle早先认为的任何系统的极限commit强度;
2、Oracle里SCN的起点是1988年1月1日;
3、_minimum_giga_scn=n的含义是把SCN往前推进到nG,但请注意,只有在SCN小于nG的时候才会用到这个隐含参数,反之则Oracle会置这个隐含参数于不顾。
求模拟_minimum_giga_scn值
这里通过时间差,大概的模拟_minimum_giga_scn小于当前时间和1988年1月1日的scn最大值(300>290)
SQL> select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss')from dual; TO_CHAR(SYSDATE,'YYYY-MM-DDHH24:MI:SS' -------------------------------------- 2012-03-18 04:27:50 SQL> select months_between(sysdate,to_date('19880101','yyyymmdd')) from dual; MONTHS_BETWEEN(SYSDATE,TO_DATE('19880101','YYYYMMDD')) ------------------------------------------------------ 290.55443 SQL> select 16384*60*60*24*31*300/(1024*1024*1024) SCN from dual; SCN ---------- 12260.7422
启动数据库测试
SQL> shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. -------------------------------- *._minimum_giga_scn=12260 -------------------------------- SQL> startup pfile='/tmp/pfile' ORACLE instance started. Total System Global Area 236000356 bytes Fixed Size 451684 bytes Variable Size 201326592 bytes Database Buffers 33554432 bytes Redo Buffers 667648 bytes Database mounted. ORA-01052: required destination LOG_ARCHIVE_DUPLEX_DEST is not specified
分析ORA-01052
SQL> !oerr ora 1052 01052, 00000, "required destination LOG_ARCHIVE_DUPLEX_DEST is not specified" // *Cause: A valid destination for parameter LOG_ARCHIVE_DUPLEX_DEST was not // specified when parameter LOG_ARCHIVE_MIN_SUCCEED_DEST was set to // two. // *Action: Either specify a value for parameter LOG_ARCHIVE_DUPLEX_DEST, or // reduce the value for parameter LOG_ARCHIVE_MIN_SUCCEED_DEST to one. SQL> show parameter LOG_ARCHIVE_DUPLEX_DEST; NAME TYPE VALUE ------------------------------------ ---------- ------------------------------ log_archive_duplex_dest string SQL> show parameter LOG_ARCHIVE_MIN_SUCCEED_DEST NAME TYPE VALUE ------------------------------------ ---------- ------------------------------ log_archive_min_succeed_dest integer 1
这里可以看出,不是以为我上面的两个参数设置错误导致ORA-01052,而是因为推进scn过大导致ORA-01052的错误
减小_minimum_giga_scn测试
这里选择_minimum_giga_scn小于当前时间和1988年1月1日的scn最大值(280<290)
SQL> select 16384*60*60*24*31*280/(1024*1024*1024) SCN from dual; SCN ———- 11443.3594 SQL> shutdown immediate ORA-01109: database not open Database dismounted. ORACLE instance shut down. —————————– *._minimum_giga_scn=11443 —————————– SQL> startup pfile=’/tmp/pfile’ ORACLE instance started. Total System Global Area 236000356 bytes Fixed Size 451684 bytes Variable Size 201326592 bytes Database Buffers 33554432 bytes Redo Buffers 667648 bytes Database mounted. Database opened. SQL> select to_char(dbms_flashback.get_system_change_number(), 2 ’9999999999999999′) from dual; TO_CHAR(DBMS_FLASHBACK.GET_SYSTEM_ ———————————- 12286827692251 SQL> select dbms_flashback.get_system_change_number()/(1024*1024*1024) from dual; DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER()/(1024*1024*1024) ———————————————————- 11443
通过试验可以发现,在我们的数据库遇到异常,需要恢复通过推进scn来恢复的时候,不是推进的越大越好;如果推进的太大可能导致ORA-01052错误,一般建议是比当前不一致的scn稍微大一点
参考:http://www.dbsnake.net/two-scn-internal-points.html
另外还有一种情况: