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.
