Thursday, July 17, 2008

V$LOG

V$LOG displays log file information from the control file.

Column
Datatype
Description
GROUP#
NUMBER
Log group number
THREAD#
NUMBER
Log thread number
SEQUENCE#
NUMBER
Log sequence number
BYTES
NUMBER
Size of the log (in bytes)
MEMBERS
NUMBER
Number of members in the log group
ARCHIVED
VARCHAR2(3)
Archive status (YES) or (NO)
STATUS
VARCHAR2(16)
Log status:
·         UNUSED - Online redo log has never been written to. This is the state of a redo log that was just added, or just after a RESETLOGS, when it is not the current redo log.
·         CURRENT - Current redo log. This implies that the redo log is active. The redo log could be open or closed.
·         ACTIVE - Log is active but is not the current log. It is needed for crash recovery. It may be in use for block recovery. It may or may not be archived.
·         CLEARING - Log is being re-created as an empty log after an ALTER DATABASE CLEAR LOGFILE statement. After the log is cleared, the status changes to UNUSED.
·         CLEARING_CURRENT - Current log is being cleared of a closed thread. The log can stay in this status if there is some failure in the switch such as an I/O error writing the new log header.
·         INACTIVE - Log is no longer needed for instance recovery. It may be in use for media recovery. It may or may not be archived.
FIRST_CHANGE#
NUMBER
Lowest system change number (SCN) in the log
FIRST_TIME
DATE
Time of the first SCN in the log

Note:
1.       Scripts using V$LOG
-- show redo log information

select group#, thread#, sequence#, (bytes/power(10,6)) MB,
       members, archived, status, first_change#,
       to_char(first_time, 'DDMonYY hh24:mi') first_time
from   V$LOG
order by first_time;

select  l.group#, member, archived, l.status, (bytes/1024/1024) fsize
from    v$log l, v$logfile f
where   f.group# = l.group#
order by 1

Oracle data dictionary views

Last updated: 2009-10-23 Friday

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