In NOLOGGING mode, data is modified with minimal logging (to mark new extents invalid and to record dictionary changes). When applied during media recovery, the extent invalidation records mark a range of blocks as logically corrupt, because the redo data is not logged. Therefore, if you cannot afford to lose this table, it is important to take a backup after the NOLOGGING operation.
And here it is from 10g:
In this mode, Oracle Database inserts data without redo or undo logging. (Some minimal logging is done to mark new extents invalid, and data dictionary changes are always logged.) This mode improves performance. However, if you subsequently must perform media recovery, the extent invalidation records mark a range of blocks as logically corrupt, because no redo data was logged for them. Therefore, it is important that you back up the data after such an insert operation.
You may recall that this used to be called UNRECOVERABLE ...
Jared
On Tue, 4 Jan 2005 15:29:32 -0800 (PST), David <thump@(protected)> wrote: > Having a bit of a debate here... > Different docs have alluded to different issues and pros/cons. > > Question....under 9i...what are the ramifications of performing the > operations that support nologging and then having to recover the database? > > These nologging operations are ongoing in such a fashion that it would not > be possible to perform a db backup after each operation. > > Can we recover and the associated objects error out with an error when > accessed and need to be recreated or can we not recover the associated > tbs/datafile at all? > > For the record....the objects assocated with the operations were we would > not need to perform logging do not need to be recovered. All objects > currently reside in the same tbs. > -- > .. > David > > -- > http://www.freelists.org/webpage/oracle-l >
-- Jared Still Certifiable Oracle DBA and Part Time Perl Evangelist -- http://www.freelists.org/webpage/oracle-l
