Oracle fast commit

Because redo log are written whenever a user commits an Oracle transaction, they can be used to speed up database operations. When a user commits a transaction, Oracle can do one of two things to get the changes into the database on the disk:

• write all the database blocks the transaction changed to their respective datafiles
• write only the redo information, which typically involves much less I/O than writing the database blocks . This recording of the changes can be replayed to reproduce all the transaction's changes later, if they are needed due to a failure.

When a user commits a transaction, Oracle guarantees that the redo for those changes writes to the redo logs on disk. The actual changed database blocks will be written out to the datafiles later.