Oracle Database Architecture Flashcards

What is an extent in Oracle's logical storage hierarchy?

Answer: A contiguous set of Oracle data blocks

An extent is a specific number of contiguous Oracle data blocks allocated at once to a segment when it needs to grow.

Which component of the shared pool stores the Oracle data dictionary cache (row cache)?

Answer: Dictionary cache

The dictionary cache (also called the row cache) within the shared pool stores frequently accessed data dictionary information to avoid repeated disk reads.

In a dedicated server configuration, how many server processes handle a single user session?

Answer: One dedicated server process per session

In dedicated server mode, Oracle spawns one dedicated server process exclusively for each user session for its entire duration.

What is the System Change Number (SCN) used for in Oracle?

Answer: Providing a consistent ordering of database changes for recovery and read consistency

The SCN is Oracle's internal timestamp that uniquely orders database changes, enabling consistent reads and precise point-in-time recovery.

Which Oracle background process performs instance recovery automatically when the database is restarted after a crash?

Answer: SMON

SMON (System Monitor) performs instance recovery at startup by rolling forward committed changes from redo logs and rolling back uncommitted transactions.

What does multiplexing the control file mean in Oracle?

Answer: Keeping multiple identical copies of the control file in different locations

Multiplexing the control file means maintaining two or more identical copies on separate disk locations so that no single disk failure can destroy all copies.

What is the smallest unit of I/O in the Oracle database storage architecture?

Answer: An Oracle data block

The Oracle data block is the smallest unit of storage that Oracle reads from and writes to disk, and its size is set at database creation.