280 | Chapter 11: Oracle and High Availability
Point-in-Time Recovery
Oracle 7.3 introduced point-in-time recovery (PITR) for the entire database. Pointin-
time recovery allows a DBA to restore the datafiles for the database and apply
redo information up to a specific time or System Change Number (SCN). This limited
type of recovery is useful for cases in which an error occurred??”for example, if a
table was dropped accidentally or a large number of rows were deleted incorrectly.
The DBA can restore the database to the point in time just prior to the event to undo
the results of the mistake.
A difficulty with database-level point-in-time recovery is that the entire database has
to be restored. In response to this limitation, Oracle8 introduced point-in-time recovery
at the tablespace level within the database. Point-in-time recovery based on a
tablespace allows a DBA to restore and recover a specific tablespace or set of
tablespaces to a particular point in time. Only the tablespace(s) containing the
desired objects need to be recovered.
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