What is the difference between sharding and partitioning?

Partitioning and sharding are methods of data division for scaling and management, but they differ in context and purpose.

Partitioning is the logical division of data within a single database or table into parts (partitions) based on a specific criterion (e.g., date or key range). This helps improve query performance and simplifies management of large data volumes, but all partitions are usually stored in one place or within a single cluster.

Sharding is the horizontal distribution of data across different servers or nodes (shards). Each shard contains a portion of the data and operates as a separate database. This allows horizontal scaling of the system, increasing overall capacity and performance.

Example:

• Partitioning: an orders table is divided into partitions by month, all partitions are on one server.
• Sharding: order data is distributed across different servers by customer ID.

Thus, partitioning is an internal storage optimization, while sharding is scaling through load distribution across machines.