SQL> select group#,sequence#,bytes,archived,status from v$log;
GROUP# SEQUENCE# BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
 1 25495 52428800 NO INACTIVE
 2 25496 52428800 NO ACTIVE
 3 25497 52428800 NO CURRENT
SQL> alter database add logfile ('+DATA','+FRA') size 250m;
Database altered.
SQL> alter database add logfile ('+DATA','+FRA') size 250m;
Database altered.
SQL> alter database add logfile ('+DATA','+FRA') size 250m;
Database altered.
SQL> select group#,sequence#,bytes,archived,status from v$log;
GROUP# SEQUENCE# BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
 1 25495 52428800 NO INACTIVE
 2 25496 52428800 NO ACTIVE
 3 25497 52428800 NO CURRENT
 4 0 262144000 YES UNUSED
 5 0 262144000 YES UNUSED
 6 0 262144000 YES UNUSED
6 rows selected.
SQL>
SQL> alter system switch logfile;
System altered.
SQL> select group#,sequence#,bytes,archived,status from v$log;
GROUP# SEQUENCE# BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
 1 25495 52428800 NO INACTIVE
 2 25496 52428800 NO ACTIVE
 3 25497 52428800 NO ACTIVE
 4 25498 262144000 NO CURRENT
 5 0 262144000 YES UNUSED
 6 0 262144000 YES UNUSED
6 rows selected.
SQL> alter system checkpoint global ;
System altered.
SQL> select group#,sequence#,bytes,archived,status from v$log;
GROUP# SEQUENCE# BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
 1 25495 52428800 NO INACTIVE
 2 25496 52428800 NO INACTIVE
 3 25497 52428800 NO INACTIVE
 4 25498 262144000 NO CURRENT
 5 0 262144000 YES UNUSED
 6 0 262144000 YES UNUSED
6 rows selected.
SQL> alter database drop logfile group 1;
Database altered.
SQL> alter database drop logfile group 2;
Database altered.
SQL> alter database drop logfile group 3;
Database altered.
SQL> select group#,sequence#,bytes,archived,status from v$log;
GROUP# SEQUENCE# BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
 4 25498 262144000 NO CURRENT
 5 0 262144000 YES UNUSED
 6 0 262144000 YES UNUSED


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