December 2002
Intermediate to advanced
928 pages
85h 29m
English
Redo log files store a “recording” of the changes made to the database as a result of transactions and internal Oracle activities. In its normal operations, Oracle caches changed blocks in memory; in the event of an instance failure, some of the changed blocks may not have been written out to the datafiles. The recording stored in the redo log can be used to play back the changes that were lost when the failure occurred.