10 Questions on Oracle Architecture.

 1. Question: What are the main components of the Oracle Database architecture?

   - Answer: The main components of Oracle Database architecture are:

     - Oracle Instance

     - Oracle Database

     - Oracle Memory Structures (SGA - System Global Area)

     - Oracle Background Processes

 

2. Question: Explain the role of the Oracle Instance.

   - Answer: The Oracle Instance is a set of memory structures and background processes that manage the Oracle Database. It includes the SGA (System Global Area) and background processes such as the listener, processes managing user sessions, and the Oracle background processes.

 

3. Question: What is the Oracle System Global Area (SGA)?

   - Answer: The SGA is a shared memory region that contains data and control information for an Oracle instance. It includes components like the Database Buffer Cache, Shared Pool, Redo Log Buffer, and other structures that are shared among multiple Oracle processes.

 

4. Question: Explain the purpose of the Database Buffer Cache in Oracle.

   - Answer: The Database Buffer Cache is part of the SGA and is used to store copies of data blocks from data files. It acts as a cache to reduce the need to read data from disk, improving overall database performance.

 

5. Question: What is the Oracle Shared Pool?

   - Answer: The Shared Pool is a component of the SGA that includes the Library Cache and the Data Dictionary Cache. It stores parsed SQL statements, execution plans, and other metadata, promoting the reuse of SQL statements and improving performance.

 

6. Question: What is the significance of the Oracle Redo Log Buffer?

   - Answer: The Redo Log Buffer is part of the SGA and is used to store redo log entries temporarily before they are written to the redo log files. It ensures the durability and recoverability of transactions.

 

7. Question: What are Oracle Background Processes?

   - Answer: Oracle Background Processes are processes that run in the background to perform various tasks. Examples include the PMON (Process Monitor), SMON (System Monitor), LGWR (Log Writer), DBWn (Database Writer), and others.

 

8. Question: Explain the role of the Oracle Listener.

   - Answer: The Oracle Listener is a process that listens for incoming connection requests from clients and establishes connections between clients and the Oracle database. It acts as a communication link between the client application and the Oracle Instance.

 

9. Question: What is the Oracle Data Dictionary?

   - Answer: The Oracle Data Dictionary is a set of tables and views containing metadata about the database. It includes information about tables, columns, indexes, privileges, and other database objects. Users and applications can query the data dictionary to retrieve information about the database structure.

 

10. Question: How does Oracle handle concurrent access to data by multiple users?

    - Answer: Oracle uses Multi-Version Concurrency Control (MVCC) to handle concurrent access to data. It allows each transaction to work with a snapshot of the data at the start of the transaction, preventing conflicts and ensuring consistency during simultaneous access by multiple users.