Oracle: log switch

A log switch occurs when the current log file is filled up.

In a log switch, a new log file is created. This is the log file that LGWR will now write to until the next log switch.

Although a new log file is created, no new online redo log file is created. Rather, some already existing online redo log files are recycled.

The log switch assigns a unique sequence number to the new log file that will hence forth be needed to identify the log file, mainly in recovery processes.

Log switches are recorded in the control file. Their history is exposed in v$log_history (and the obsolete v$loghist).