OCP Database Architecture & Configuration 2 — Questions and Answers
Question 1: Which Oracle background process is responsible for writing modified data blocks from the buffer cache to datafiles?
- LGWR
- DBWR (Correct answer)
- CKPT
- SMON
Correct answer: DBWR
DBWR (Database Writer) writes dirty buffers from the buffer cache to datafiles on disk.
Question 2: What is the purpose of the UNDO tablespace in Oracle Database?
- Store temporary sort segments
- Store rollback information for active transactions (Correct answer)
- Store redo log entries
- Store data dictionary metadata
Correct answer: Store rollback information for active transactions
The UNDO tablespace stores before-image data needed to roll back transactions and provide read consistency.
Question 3: Which initialization parameter controls the total size of the System Global Area (SGA)?
- DB_CACHE_SIZE
- SGA_TARGET (Correct answer)
- SHARED_POOL_SIZE
- MEMORY_TARGET
Correct answer: SGA_TARGET
SGA_TARGET enables Automatic Shared Memory Management (ASMM) and sets the total SGA size.
Question 4: What does a checkpoint event accomplish in Oracle Database?
- Flushes the shared pool
- Updates datafile headers with the current SCN and signals DBWR to write dirty buffers (Correct answer)
- Archives the current redo log
- Resets the log sequence number
Correct answer: Updates datafile headers with the current SCN and signals DBWR to write dirty buffers
A checkpoint updates all datafile headers with the current checkpoint SCN and triggers DBWR to write dirty buffers to disk.
Question 5: In Oracle's multi-tenant architecture, which component hosts the application data for a pluggable database?
- CDB$ROOT
- PDB$SEED
- The PDB itself (Correct answer)
- The CDB metadata catalog
Correct answer: The PDB itself
Each PDB contains its own application data, local users, and objects independent of the CDB root.
Question 6: Which Oracle feature allows online movement of datafiles without taking them offline?
- RMAN restore
- Online datafile move (ALTER DATABASE MOVE DATAFILE) (Correct answer)
- Transportable tablespace
- Data Pump export
Correct answer: Online datafile move (ALTER DATABASE MOVE DATAFILE)
The ALTER DATABASE MOVE DATAFILE command moves a datafile to a new location while the database remains open and accessible.
Question 7: What is the minimum number of redo log groups required for an Oracle database to function?
- 1
- 2 (Correct answer)
- 3
- 4
Correct answer: 2
Oracle requires at least 2 redo log groups so that LGWR can switch between groups during a log switch.
OCP Database Architecture & Configuration 2
Which Oracle background process is responsible for writing modified data blocks from the buffer cache to datafiles?