Oracle Database Administration from Zero to Hero - Managing Undo Data (Part 1 of 3)

The video tutorial covers the concept of undo data in Oracle databases, explaining its benefits, such as rollback, read consistency, and recovery from failed transactions. It details the DML life cycle, undo generation, and the importance of undo retention. The tutorial also outlines tasks for DBAs to manage undo data effectively, including setting parameters for undo management and retention.

What is one of the primary benefits of undo data in Oracle databases?

• It helps in managing user permissions.

• It enhances data encryption.

• It supports rollback operations.

• It speeds up data retrieval.

In the DML life cycle, what happens when a user updates a row in the database?

• The row is moved to a new table.

• The row is duplicated.

• A lock is applied to the row.

• The row is immediately deleted.

What is the role of active undo in a transaction?

• It stores the before-update image of a row.

• It is used for data encryption.

• It deletes old data.

• It compresses the data.

How does undo data support read consistency?

• By allowing multiple users to update the same row simultaneously.

• By providing the updated image of a row to all users.

• By ensuring readers see the data as it was at the time of their query.

• By preventing any changes to the data.

What happens if a transaction fails before it is committed?

• The transaction is committed automatically.

• The transaction is saved for later.

• The database automatically rolls back the transaction.

• The transaction is ignored.

What is the default setting for the undo management parameter in Oracle databases?

• User-defined

• Semi-automatic

• Automatic

• Manual

What is the purpose of the undo retention parameter?

• To determine the size of the database.

• To specify how long old undo data is retained before being overwritten.

• To define the encryption level of the database.

• To set the number of users allowed to access the database.

What error might occur if a long-running query cannot find the required rows in the old undo?

• ORA-00001: unique constraint violated

• ORA-01555: snapshot too old

• ORA-00942: table or view does not exist

• ORA-01722: invalid number

What is the recommended setting for the undo management parameter?

• Manual

• Automatic

• Semi-automatic

• User-defined

What is the role of expired undo in the undo tablespace?

• It is used for new active transactions.

• It is permanently deleted.

• It is archived for future use.

• It is used to create new tables.