Once a tablespace is in read-only mode, it can be backed up once and doesn??™t have
to be backed up again, since its contents cannot change unless it??™s placed in read/
write mode. Marking a tablespace as read-only allows entire sections of a database to
be marked read-only, backed up once, and excluded from regular backups thereafter.
If a datafile of a read-only tablespace is damaged, youcan restore it directly from the
backup without any recovery. Because no changes were made to the datafiles, no
redo log information needs to be applied. For databases with significant static or historical
data, this option can significantly simplify and streamline backup and restore
operations.
Read-only tablespaces, combined with Oracle??™s ability to partition a table on a range
or list of column values (for example, a date) provide powerful support for the rolling
windows common to data warehouses (described in Chapter 10). Once a new
month??™s data is loaded, indexed, and so on, the relevant tablespaces can be marked
read-only and backed up once, removing the tablespaces datafile(s) from the cycle of
ongoing backup and significantly reducing the time required for those backup
operations.
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