Redis Cluster is Redis's native sharding mode. A cluster of Redis nodes partitions the keyspace into 16,384 hash slots; each node owns a contiguous range of slots; clients learn which node owns which slot and route commands directly. Redis Cluster combines sharding with replication for horizontal scale and availability.
Key concepts
Sharding is the practice of horizontally partitioning a dataset across multiple database instances so each shard holds a subset of the data and serves a subset of the load. Sharding is the standard answer when a single database server cannot keep up with storage, read throughput, or write throughput.
How it works
A shard key (one or more fields) determines which shard each row or document…
A replica set is MongoDB's name for a group of database nodes that maintain the same data and provide automatic failover. One node is the primary (accepts writes); the rest are secondaries that asynchronously apply the primary's operation log. If the primary becomes unreachable, the secondaries elect a new primary among themselves.
How it works
Writes go to the primary, which records them in…
MySQL is one of the most widely deployed open-source relational databases, especially common in web stacks and as the storage layer behind countless WordPress, Rails, and PHP applications. It is owned by Oracle, with two prominent community forks: MariaDB (separate project since 2010) and Percona Server (a drop-in replacement with operational tooling).
Key features
MongoDB is an open-source document database that stores data as BSON documents grouped into collections. Each document is a self-contained JSON-like object with a flexible schema.
Key features