A Beginner-Friendly Guide to Oracle Database Architecture

Over the next few days, I’ll be sharing the basic architecture of the Oracle Database in simple terms. This series is designed for beginners who want to understand what Oracle Database is and how it works. If that sounds like you, stay tuned and follow and subscribe so you don’t miss any of the posts.

What is a Database?

When you hear about databases, think of a repository. It is basically a collection of records that stores what users do. It is a repository for application data.

Types of Database

There are two major kinds of databases.

Relational databases i.e. Oracle,MSSQL, Postgres etc. and non-relational/no-sql databases i.e. MongoDB, Casandra etc.

What is RDBMS?

Relational database management systems are databases whose data is stored in tables as rows and columns.

They contain structured data unlike no-sql databases that contain unstructured data.

A major attribute of an RDBMS is that it follows the ACID principle.

ACID Explained

ACID is an acronym.

Atomicity

A transaction is all or nothing

If a part of the transaction fails, the entire transaction is rolled back.

That way, a transaction is either committed or rolled back.

Consistency

At every point, the database remains complete, correct and reliable-before and after every transaction.

Isolation

Transactions are independent.

Changes only take effect after they are committed which ensures the data integrity.

Durability

It is expected that once a record is committed it becomes permanent regardless of the situation.

Database Architecture

Oracle database can be deployed in three main forms.

Single Instance Database

One instance(memory structure + background processes) connecting to one database.

Real Application Cluster(RAC)

Multiple instances connecting to a single shared database.

Multitenant database

Introduced in Oracle 12c

Comprises one container database with one or more pluggable databases.

Relationship between Instance and Database