Log Writer (LGWR)
LGWR performs sequential writes from the Redo Log Buffer to the online redo log file under the following situations:
•1.When a transaction commits
•2.When the Redo Log Buffer is one-third full
•3.When there is more than 1 MB of changes recorded in the Redo Log Buffer
•4.Before DBWn writes modified blocks in the Database Buffer Cache to the data files
•5.Every three seconds
.Because the redo is needed for recovery, LGWR confirms the commit operation only after the redo is written to disk.
LGWR can also call on DBWn to write to the data files.
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