【翻譯自mos文章】ORA-19815, Flashback Logs-Space management，

【翻譯自mos文章】ORA-19815, Flashback Logs-Space management，

ORA-19815, Flashback Logs-Space management (文檔 ID 369755.1)

適用於：
Oracle Database - Enterprise Edition - Version 10.1.0.2 to 11.2.0.3 [Release 10.1 to 11.2]
Information in this document applies to any platform.
 ***Checked for relevance on 08-Jan-2014***

目標：
recovery file dest被flashback log 撐爆了，在alert日誌中報ora-19815錯誤，需要remove or reuse 掉flashback log（FBL）

解決方案：
flashback logs 是被oracle 內部處理的，dba不能控制flashback logs。這意味著dba不能手工delete flashback logs，唯一的方法是disable掉 flashback

The FlashBack Logs can ONLY be deleted by DISABLING FLASHBACK  on database level
SQL> startup mount
      alter database flashback off;
      alter database open;

當遇到空間壓力時，flashback log 基於如下2種情況被deleted

1）當一個歸檔日誌被deleted時，oracle 會delete 掉 被歸檔日誌所依賴的flashback logs

2）當quota被收縮時，flashback log 被deleted以回收disk space
   減小DB_RECOVERY_FILE_DEST_SIZE參數值到一個特定值，以便讓flashback log 遇到space pressure，老的flashback log 將會被deleted

我們可能遇見下面的bug：即使遇到fra區中的空間壓力，flashback log 也不會被deleted。

Bug 5106952  FLASHBACK LOG SPACE NOT BEING RECLAIMED
Fixed In Ver: 11.0
Also the bug is  fixed in patch set 10.1.0.6  and 10.2.0.3 .

雖然Bug 5106952 在11g中被fix了，這個過程依然可以被用來delete flashback log

1.- First of all we need to check if there is any guaranteed restore point defined:     SQL> select name,scn,time,database_incarnation#,guarantee_flashback_database,storage_size from v$restore_point; 2.- Remove all the restore points     SQL> Drop restore point <name>;  3.- Check how much space is used before turning off Flashback     SQL> select * from v$flash_recovery_area_usage; 4.- SQL> ALTER DATABASE FLASHBACK OFF; 5.-  Now you can delete the Flashback logs manually 6.- SQL> ALTER DATABASE FLASHBACK ON; 7.- Check that there are no flashback logs before turning back on       SQL> select * from v$flash_recovery_area_usage;