Question: What is a clustered database?

Answer

A clustered database is a database that is spread across multiple computing or storage units, known as nodes, which are interconnected to work as a single system. This architecture enhances the performance, scalability, and availability of databases.

Key Features

• High Availability: By distributing data across multiple nodes, clustered databases ensure that the failure of one node doesn't lead to downtime, as other nodes can take over the workload.
• Scalability: You can add more nodes to scale out resources and handle increased load without significant downtime.
• Load Balancing: Requests can be distributed across nodes to balance the load, preventing any single node from becoming a bottleneck.

Types of Clustered Databases

1. Shared-Disk Clustering: All nodes access the same disk storage, allowing any node to serve any request. It simplifies data management but requires a high-speed network for effective performance.

2. Shared-Nothing Clustering: Each node has its own disk storage. Data is partitioned across nodes, and each node handles transactions for its own data. This approach scales well and avoids the potential bottleneck of shared-disk systems.

Example: MySQL Cluster

MySQL Cluster is an example of a shared-nothing clustered database. It's designed for high availability and scalability, distributing data across multiple nodes to achieve fault tolerance and improve read/write operations.

-- Creating a table in MySQL Cluster
CREATE TABLE test_table (
    id INT NOT NULL AUTO_INCREMENT,
    value VARCHAR(100),
    PRIMARY KEY (id)
) ENGINE=NDB;

This SQL statement creates a table using the NDB storage engine, which is used for clustering in MySQL. The NDB engine ensures that the data is automatically partitioned across different nodes in the cluster.

Conclusion

Clustered databases are essential in environments requiring high availability, scalability, and efficient processing of large volumes of transactions. By leveraging a cluster of servers, these databases can provide continuous service and manage growing data needs effectively.