OCP exam notes 1z0-052

1 about undo
The database can have more than one undo tablespace;
Undo segments can automatically grow, shrink on demand

2 about Oracle Data Dump export and import
You can change the table name during the import operation;
You can override an existing dumpfile during the export operation.

3. About invalid Indexes
Will be ignored by the optimizer;
It can only take effect through rebuild.

4. About listeners
Multiple listeners can run on one host;
Multiple databases can be registered on one listener.

5 about ADDM
ADDM runs after each AWR snapshot is collected automatically by MMON.
The results of the ADDM analysis are stored in th AWR.

6. About Checkpoint
It ensures that all committed data is written to the data files during normal shutdown.
The frequent full checkpoint in a database can cause the overall degradation of the database performance.

7 about B-tree indexes
The leaf blocks in the index are doubly linked.
The deletion of a row frin the table cause a logical deletion in index leaf block and the space becomes available for the nre leaf entry.

8 about sessions
Multiple transactions can use the same undo segment.
A transaction is assigned an undo segment when it is started.