闪回日志清理规则
oracle flashbackup logs auto space management.
Case 1 (Demo :changing retention)
=================================
SQL> select * from v$flash_recovery_area_usage;
FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----------------------- ------------------ ------------------------- --------------- ----------
CONTROL FILE 0 0 0 0
REDO LOG 0 0 0 0
ARCHIVED LOG 11.58 0 32 0
BACKUP PIECE .18 0 2 0
IMAGE COPY 0 0 0 0
FLASHBACK LOG 18.75 0 17 0
FOREIGN ARCHIVED LOG 0 0 0 0
AUXILIARY DATAFILE COPY 0 0 0 0
8 rows selected.
SQL> select NAME,PDB_RESTORE_POINT,CLEAN_PDB_RESTORE_POINT,SCN,DATABASE_INCARNATION#,GUARANTEE_FLASHBACK_DATABASE from v$restore_point;
no rows selected
SQL> show parameter flash
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_flash_cache_file string
db_flash_cache_size big integer 0
db_flashback_retention_target integer 4096
SQL> alter system set db_flashback_retention_target=2048;
System altered.
SQL> select * from v$flash_recovery_area_usage;
FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----------------------- ------------------ ------------------------- --------------- ----------
CONTROL FILE 0 0 0 0
REDO LOG 0 0 0 0
ARCHIVED LOG 11.58 0 32 0
BACKUP PIECE .18 0 2 0
IMAGE COPY 0 0 0 0
FLASHBACK LOG 2.34 1.17 2 0
FOREIGN ARCHIVED LOG 0 0 0 0
AUXILIARY DATAFILE COPY 0 0 0 0
8 rows selected.
SQL>
SQL>
SQL>
SQL> alter session set NLS_DATE_FORMAT='DD-MM-YY HH24:MI:SS';
Session altered.
SQL> select * from v$flashback_database_log;
OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_ RETENTION_TARGET FLASHBACK_SIZE ESTIMATED_FLASHBACK_SIZE CON_ID
-------------------- ----------------- ---------------- -------------- ------------------------ ----------
2867919 25-10-18 02:56:27 2048 503316480 1018027485 0
Alert
=====
2018-10-25T05:55:06.769584+00:00
Deleted Oracle managed file /<path>/o1_mf_fwv27fht_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv27jfp_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv8gco9_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv8jgph_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv8m43o_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv8ozz3_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv8rll9_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv8vtdg_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv8yzt5_.flb
2018-10-25T05:55:07.886981+00:00
Deleted Oracle managed file /<path>/o1_mf_fwv92klo_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv96csg_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv9p7ln_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv9qoqt_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv9s0gn_.flb
Deleted Oracle managed file /<path>/o1_mf_fwv9th7q_.flb
2018-10-25T05:55:08.560934+00:00
ALTER SYSTEM SET db_flashback_retention_target=2048 SCOPE=BOTH;
Case 2 (Demo: change in time)
==============================
SQL> select * from v$flash_recovery_area_usage;
FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----------------------- ------------------ ------------------------- --------------- ----------
CONTROL FILE 0 0 0 0
REDO LOG 0 0 0 0
ARCHIVED LOG 22.42 0 71 0
BACKUP PIECE .62 .36 13 0
IMAGE COPY 0 0 0 0
FLASHBACK LOG 3.52 0 5 0
FOREIGN ARCHIVED LOG 0 0 0 0
AUXILIARY DATAFILE COPY 0 0 0 0
8 rows selected.
SQL> alter session set NLS_DATE_FORMAT='DD-MM-YY HH24:MI:SS';
Session altered.
SQL> select sysdate, min(first_time), (sysdate-min(first_time))*24*60 from v$flashback_database_logfile;
SYSDATE MIN(FIRST_TIME) (SYSDATE-MIN(FIRST_TIME))*24*60
----------------- ----------------- -------------------------------
26-10-18 14:36:05 25-10-18 10:22:42 1693.38333
SQL>select * from v$flash_recovery_area_usage;
FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----------------------- ------------------ ------------------------- --------------- ----------
CONTROL FILE 0 0 0 0
REDO LOG 0 0 0 0
ARCHIVED LOG 23.59 0 73 0
BACKUP PIECE .62 .36 13 0
IMAGE COPY 0 0 0 0
FLASHBACK LOG 4.82 0 7 0
FOREIGN ARCHIVED LOG 0 0 0 0
AUXILIARY DATAFILE COPY 0 0 0 0
8 rows selected.
SQL> select sysdate from dual;
SYSDATE
-----------------
26-10-18 14:38:01
<<Changed the system date by 1 day ahead>>
SQL> select sysdate from dual;
SYSDATE
-----------------
27-10-18 14:39:36
SQL> select * from v$flash_recovery_area_usage;
FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----------------------- ------------------ ------------------------- --------------- ----------
CONTROL FILE 0 0 0 0
REDO LOG 0 0 0 0
ARCHIVED LOG 24.75 0 75 0
BACKUP PIECE .62 .36 13 0
IMAGE COPY 0 0 0 0
FLASHBACK LOG 5.47 4.17 8 0 << Space reclaimable
FOREIGN ARCHIVED LOG 0 0 0 0
AUXILIARY DATAFILE COPY 0 0 0 0
8 rows selected.
SQL> select sysdate, min(first_time), (sysdate-min(first_time))*24*60 from v$flashback_database_logfile;
SYSDATE MIN(FIRST_TIME) (SYSDATE-MIN(FIRST_TIME))*24*60
----------------- ----------------- -------------------------------
27-10-18 14:40:51 25-10-18 10:22:42 3138.15
SQL> select sysdate, min(first_time), (sysdate-min(first_time))*24*60 from v$flashback_database_logfile;
SYSDATE MIN(FIRST_TIME) (SYSDATE-MIN(FIRST_TIME))*24*60
----------------- ----------------- -------------------------------
27-10-18 14:43:47 26-10-18 14:32:31 1451.26667
SQL> select * from v$flash_recovery_area_usage;
FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----------------------- ------------------ ------------------------- --------------- ----------
CONTROL FILE 0 0 0 0
REDO LOG 0 0 0 0
ARCHIVED LOG 25.3 0 76 0
BACKUP PIECE .62 .36 13 0
IMAGE COPY 0 0 0 0
FLASHBACK LOG 5.47 1.95 8 0
FOREIGN ARCHIVED LOG 0 0 0 0
AUXILIARY DATAFILE COPY 0 0 0 0
8 rows selected.
