Oracle Database Architecture Flashcards

Which SGA component is allocated per-server and stores session-specific data such as sort areas and cursor state?

Answer: Program Global Area (PGA)

The PGA (Program Global Area) is private memory allocated for each server process, storing session-specific data like sort work areas and bind variable values.

What happens to the redo log buffer entries when it is one-third full or a COMMIT is issued?

Answer: LGWR writes them to the redo log files

LGWR writes redo log buffer contents to the online redo log files when triggered by a COMMIT, when the buffer is one-third full, or every three seconds.

Which Oracle startup mode allows the DBA to perform maintenance but prevents regular users from connecting?

Answer: OPEN RESTRICTED

OPEN RESTRICTED mode opens the database but limits access to users with the RESTRICTED SESSION privilege, allowing DBA maintenance tasks.

What is the function of the CKPT (Checkpoint) process?

Answer: Updating data file headers and the control file with the latest checkpoint SCN

CKPT updates the headers of data files and the control file with the current checkpoint System Change Number (SCN) after a checkpoint event.

In Oracle architecture, what is a segment?

Answer: A set of extents that store a specific type of database object

A segment is a set of extents allocated for a specific database object such as a table, index, or undo data within a tablespace.

Which file must Oracle open during the MOUNT startup stage before the database can be fully opened?

Answer: Control file

During the MOUNT stage, Oracle opens the control file to read the locations and names of all data files and redo log files.

What is the purpose of the ARCn (Archiver) background process?

Answer: Copying filled online redo log groups to archive log destinations

ARCn automatically copies filled online redo log files to archive log destinations when the database is in ARCHIVELOG mode.