Redo Log Buffer

Redo Log Buffer

Oracle database keeps record of changes made to data. Every time user performs a DML, DDL or DCL operation, its redo entries are also created. Redo entries contain the information necessary to reconstruct, or redo, changes made to the database by INSERT, UPDATE, DELETE, CREATE, ALTER, or DROP operations. Redo entries are used for database recovery, if necessary. Oracle Database processes copy redo entries from the user memory space to the redo log buffer in the SGA. The redo entries take up continuous, sequential space in the buffer. The background process log writer (LGWR) writes the redo log buffer to the active online redo log group on disk
If database is running in archiving mode then archive log files are created from redo log files. These archive log files are used to in various database recovery techniques.

LOG_BUFFER initialization parameter is used to set the size Redo Log buffer