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Redo log switch

A log switch occurs when one online redo log has been filled and the next online redo log is going to be filled. A log switch always triggers a checkpoint.

Relation to checkpoint

A redo log switch triggers a checkpoint, however the converse is not true;
SQL> select sequence# from v$log where status = 'CURRENT';

 SEQUENCE#
----------
       523

SQL> alter system switch logfile;

System altered.

SQL> select sequence# from v$log where status= 'CURRENT';

 SEQUENCE#
----------
       524

SQL> alter system checkpoint;

System altered.

SQL> select sequence# from v$log where status = 'CURRENT';

 SEQUENCE#
----------
       524

Reason for checkpoint

..... yet to be done...