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Flashback Database Logs can exceed the Retention Target

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The documentation on the Flashback Retention Target in 11.2 and 1 2.1 states that this parameter specifies an upper limit on how far the database may be flashed back.

However, if the FRA (db_recovery_file_dest_size) is actually large enough, Oracle may retain flashback logs for a much longer duration.

SQL> alter session set nls_date_format='DD-MON-RR HH24:MI:SS'; Session altered. SQL> select sysdate, l.* from v$flashback_database_log l; SYSDATE OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_T RETENTION_TARGET ------------------ -------------------- ------------------ ---------------- FLASHBACK_SIZE ESTIMATED_FLASHBACK_SIZE -------------- ------------------------ 29-OCT-16 07:42:44 6968261 28-OCT-16 22:35:50 180 157286400 86467584 SQL> SQL> show parameter flashback NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_flashback_retention_target integer 180 SQL> SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup mount ORACLE instance started. Total System Global Area 1068937216 bytes Fixed Size 2260088 bytes Variable Size 750781320 bytes Database Buffers 310378496 bytes Redo Buffers 5517312 bytes Database mounted. SQL> flashback database to timestamp trunc(sysdate); Flashback complete. SQL>

Thus, it is useful to check the V$FLASHBACK_DATABASE_LOG, V$FLASHBACK_DATABASE_LOGFILE and V$FLASHBACK_DATABASE_STAT and V$FLASH_RECOVERY_AREA_USAGE views from time to time.

See Oracle Support Doc# 1194013.1 for a discrepancy between the first two views.

Note : If you have Standby database configured, also see John Hallas's blog post .

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