Introduction

Oracle Database is a relational database management system (RDBMS) developed by Oracle Corporation. It is one of the most popular and widely used RDBMSs in the world, used by businesses of all sizes in a wide variety of industries.

What is the top use cases of Oracle Database?

Oracle Database has a wide range of use cases across various industries. Some of the top use cases include:

1. Enterprise Applications: Oracle Database is commonly used to power large-scale enterprise applications such as customer relationship management (CRM), enterprise resource planning (ERP), and supply chain management (SCM) systems.
2. Data Warehousing: Oracle Database provides robust features for data warehousing, allowing organizations to store and analyze large amounts of data for business intelligence and reporting purposes.
3. Online Transaction Processing (OLTP): Oracle Database is highly optimized for handling online transaction processing workloads, making it suitable for applications that require fast and reliable data processing.
4. Cloud Computing: Oracle offers a cloud-based version of its database, known as Oracle Autonomous Database, which provides high availability, scalability, and security for cloud-native applications.

What are the features of Oracle Database?

Oracle Database offers a wide range of features that make it a powerful and flexible database management system. Some of the key features include:

1. Data Security: Oracle Database provides advanced security features such as data encryption, fine-grained access control, and auditing capabilities to protect sensitive data.
2. High Availability: Oracle Database supports various high availability features, including data replication, automatic failover, and online backup and recovery, to ensure continuous access to data.
3. Scalability: Oracle Database can scale vertically and horizontally to handle growing data volumes and user loads. It supports clustering, partitioning, and parallel processing for improved performance.
4. Data Integration: Oracle Database offers robust data integration capabilities, including support for data import/export, data transformation, and data synchronization with other systems.

What is the workflow of Oracle Database?

The workflow of Oracle Database involves several key steps:

1. Database Creation: The first step is to create a new database or use an existing one. This involves defining the database structure, including tables, indexes, and other database objects.
2. Data Loading: Once the database is created, data can be loaded into the database from various sources, such as files or other databases.
3. Data Manipulation: After the data is loaded, it can be manipulated using SQL (Structured Query Language) statements. This includes inserting, updating, deleting, and querying data.
4. Data Backup and Recovery: Regular backups of the database are taken to protect against data loss. In case of any failure or data corruption, the database can be restored from backups.
5. Performance Tuning: Oracle Database provides various tools and techniques for performance tuning, such as optimizing SQL queries, configuring indexing, and monitoring system performance.
6. Security and Access Control: Oracle Database allows administrators to define security policies and access controls to ensure the confidentiality, integrity, and availability of data.

How Oracle Database Works & Architecture?

Oracle Corporation developed and marketed Oracle Database, a widely used relational database management system (RDBMS). Renowned for its reliability, scalability, and performance, Oracle Database supports various programming languages and development frameworks, making it a preferred choice for storing and retrieving data across diverse applications. Its capabilities span data warehousing, online transaction processing, advanced analytics, high availability, disaster recovery, and robust security measures.

Following a client-server architecture, Oracle Database has separate processes for the database server and client connections. The server process manages data and resources, while client connections interact with the server to manipulate and access data. Supported programming interfaces include SQL, PL/SQL (Oracle’s proprietary procedural language), and Java. The system also offers tools for efficient database management and administration, such as Oracle Enterprise Manager and SQL Plus.

The architecture of Oracle Database comprises:

• Memory structure(Instances)
• Database system 
• Processes

Oracle Instances

An Oracle instance comprises two essential components:

System Global Area (SGA):
The SGA, or System Global Area, represents a shared memory area. When a database instance initiates, a portion of memory is allocated, known as SGA. Concurrently, one or more background processes are launched. SGA is utilized for storing both data and control information pertaining to a specific database instance. Its various subcomponents, each dedicated to a specific purpose, include:

• Database Buffer Cache:
  A segment of the SGA, the Buffer Cache stores copies of data blocks retrieved from datafiles. It serves to cache frequently accessed data blocks, minimizing the need for disk I/O operations and thereby enhancing performance by expediting data retrieval.
• Redo Log Buffer:
  Vital for recovery operations, the redo log is comprised of preallocated files storing real-time changes made to the database. Every Oracle Database instance is associated with a redo log, safeguarding the database against instance failures.
• Java Pool:
  An optional segment of the SGA utilized by the Java Virtual Machine (JVM) and related components. The Java Pool stores Java-related data structures, such as classes and objects, and is activated when the Oracle Database is configured for Java applications or Oracle JVM usage.
• Large Pool:
  Another optional SGA segment designated for substantial memory allocations, particularly useful for tasks like backup and restore operations and I/O server processes. Its primary function is to enhance performance in these operations by minimizing disk I/O requirements.
• Shared Pool:
  A portion of the SGA containing shared memory structures like shared SQL and PL/SQL areas. The Shared Pool stores parsed representations of SQL statements, execution plans, and PL/SQL program units, facilitating efficient reuse of frequently executed statements and improving overall performance.

Background Processes:
Oracle employs background processes responsible for memory management, I/O operations, and other maintenance tasks. Notable background processes include:

• System Monitor Process (SMON):
  Responsible for system-level recovery and maintenance activities.
• Process Monitor Process (PMON):
  Monitors other background processes.
• Database Writer Process (DBWR):
  Writes data blocks from the Database Buffer Cache (in SGA) to physical data files in the database system.
• Log Writer Process (LGWR):
  Writes Redo blocks from the Redo Log Buffer (in SGA) to Redo Log Files in the database system.
• Checkpoint (CKPT):
  Maintains data files and control files with the latest checkpoint information.

Database System

A database system is designed for the storage system of a computer, essentially serving as the repository for files. Within the database system, three main categories of files exist:

1. Data Files: These files store the actual data within the database.
2. Redo Log Files: Utilized to capture changes made in the database, these files play a crucial role in the recovery process by restoring the original information.
3. Control Files: As binary files, control files contain database status-related information such as the Database Name, Data File and Redo Log file Names, File Locations, and Log Sequence Number. Additional file categories contribute to effective database management:

• Parameter File: Housing parameters defining the startup configuration of the database.
• Password File: Responsible for storing user passwords, ensuring the security of databases.

Processes

There are two distinct types of processes:

1. User Process: Also referred to as the client process, the user process facilitates the connection to the instance. It becomes active when a user sends a connection request to the Oracle server.
2. Server Process: This process establishes the connection between the user and the database, executing activities on behalf of the client such as SQL statement execution and data retrieval.