Advance Database Systems

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A distributed database system (DDBS) is a collection of logically interrelated databases distributed over a computer network. These systems make the distribution transparent to you, meaning you can interact with it as if it were a single, centralized database.

The main reasons for using a DDBS are:

When you submit a SQL query, it doesn't immediately translate into data being retrieved. Instead, it goes through several stages to ensure it's valid and executed efficiently. This entire process is called query processing. The goal of query optimization is to find the most cost-effective execution plan for a given query.

Big Data isn't just about size; it's often characterized by the "3 Vs": Volume, Velocity, and Variety.
- Volume: Sheer amount of data (terabytes, petabytes, zettabytes).
- Velocity: Speed at which data is generated, processed, and analyzed (e.g., real-time sensor data, social media feeds).
- Variety: Diverse types of data (structured, semi-structured, unstructured like text, images, videos).

When you interact with a database, you're often performing a series of actions that should either all succeed or all fail together. This group of actions is called a transaction. For example, transferring money from account A to account B isn't just one step; it's deducting from A and adding to B. If only one part happens, your bank's books are wrong!

As data grows in volume, variety, and velocity, traditional relational databases (SQL) sometimes hit their limits. This has led to new database types and advanced techniques.

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