What are
|
Block | Description |
---|---|
segment header | The problem is probably a freelist contention. |
data block | Increasing the size of the database buffer
cache can help to reduce these waits; but this can also point
to freelist contention. |
undo header | If you don't use Undo TableSpaces, you probably have too few rollback segments. |
undo block |
Beside tuning the FREELISTS
and FREELIST GROUPS
parameter for each single object (which is a bunch of work and, at least for
FREELIST GROUPS
, requires a complete rebuild of the affected
table), there's something new with Oracle 9i: If you use locally managed
tablespaces, you may benefit from a new feature called ASSM, Automatic
Segment Space Management. This is defined at tablespace level on creation of
the same - which means, you cannot change it for existing tablespaces but
must create a new tablespace and move all objects there:
CREATE TABLESPACE index01
DATAFILE '/disk1/oraData/index01.dbf' SIZE 750M AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED EXTENT MANAGEMENT LOCAL SEGMENT SPACE MANAGEMENT AUTO |
One side effect to consider is, that at least with Oracle 9i LOB objects are not supported with ASSM. So if you have LOB objects and want to use ASSM, you must create a separate tablespace for the LOB objects that does not use ASSM. For index tablespaces this shouldn't be a restriction, since one normally should not have LOB objects there.