Oracle Database Architecture Flashcards

Which SGA component stores the most recently executed SQL statements and their execution plans?

Answer: Shared pool

The shared pool contains the library cache, which stores parsed SQL statements and execution plans for reuse.

What is the primary role of the PMON (Process Monitor) background process?

Answer: Cleaning up after failed user processes

PMON detects failed user processes and cleans up the cache and releases resources such as locks that the failed process held.

In Oracle, which type of file records all changes made to the database and is critical for instance recovery?

Answer: Redo log files

Redo log files record all changes (redo entries) to the database and are used to recover committed transactions after a failure.

What does the term 'Oracle instance' specifically refer to?

Answer: The combination of SGA and background processes

An Oracle instance is defined as the combination of the System Global Area (SGA) memory structure and the Oracle background processes.

Which background process is responsible for writing modified data blocks from the buffer cache to the data files?

Answer: DBWn

DBWn (Database Writer) writes dirty (modified) buffers from the database buffer cache to the data files on disk.

A tablespace in Oracle is best described as which type of structure?

Answer: A logical storage container made up of one or more data files

A tablespace is a logical storage unit in Oracle that corresponds physically to one or more data files on the operating system.

Which Oracle memory structure temporarily stores transaction undo information to support read consistency and rollback?

Answer: Undo tablespace segments

Undo segments (stored in the undo tablespace) hold before-images of changed data to support rollback operations and read-consistent queries.