Amazon ElastiCache vs Amazon RDS for PostgreSQL: What are the differences?

Introduction

Amazon ElastiCache and Amazon RDS for PostgreSQL are both managed database services provided by Amazon Web Services (AWS). While they serve similar purposes, there are key differences between the two. This article aims to provide a comparison of Amazon ElastiCache and Amazon RDS for PostgreSQL.

1. Deployment of Caching vs Relational Database: Amazon ElastiCache is primarily designed for caching purposes, enabling you to deploy an in-memory cache service such as Redis or Memcached. On the other hand, Amazon RDS for PostgreSQL is a fully managed relational database service, allowing you to deploy and manage PostgreSQL databases.

2. Data Structure: Key-Value store vs Relational Database: Amazon ElastiCache is optimized for key-value data, making it suitable for caching scenarios where simple key-value lookups are required. In contrast, Amazon RDS for PostgreSQL provides a relational database management system that supports a rich set of SQL features and complex data structures.

3. Scaling: Horizontal Scaling vs Vertical Scaling: With Amazon ElastiCache, horizontal scaling is the primary method of scaling. The cache nodes can be added or removed to handle varying workload demands. On the other hand, Amazon RDS for PostgreSQL allows both horizontal and vertical scaling. You can horizontally scale by adding read replicas and vertically scale by increasing the compute and storage capacity of the database instance.

4. Replication and High Availability: Amazon ElastiCache provides automatic replication and high availability for caching data, allowing you to easily recover from failures. Amazon RDS for PostgreSQL also supports replication and high availability through features like Multi-AZ (Availability Zone) deployments and read replicas. This ensures data durability and availability.

5. Data Persistence: Volatile vs Durable: Amazon ElastiCache is designed to be an in-memory cache, which means the data stored in the cache is volatile. In contrast, Amazon RDS for PostgreSQL provides durable storage for your data, ensuring data persistence even in the event of failures or restarts.

6. Backup and Restore: Amazon RDS for PostgreSQL offers automated backup and restore features, allowing you to easily create backups, restore to a point-in-time, and recover data in case of data loss or corruption. Amazon ElastiCache does not provide native backup and restore functionality since it is intended for caching purposes rather than long-term data storage.

In Summary, Amazon ElastiCache is a caching service optimized for key-value data with horizontal scaling, while Amazon RDS for PostgreSQL is a managed relational database service with support for complex data structures, vertical and horizontal scaling, as well as backup and restore capabilities.