Key-Value Database

What is a key-value database?#

Key-value databases are also a part of the NoSQL family. These databases use a simple key-value pairing method to store and quickly fetch the data with minimum latency.

Features of a key-value database#

Due to the minimum latency they ensure, that is constant O(1) time, the primary use case for these databases is caching application data.

The key serves as a unique identifier and has a value associated with it. The value can be as simple as a string and as complex as an object graph.

The data in key-value databases can be fetched in constant time O(1), and there is no query language required to fetch the data. It’s just a simple no-brainer fetch operation. This ensures minimum latency.

As discussed earlier in the course, these databases are also used to achieve a consistent state in distributed systems.

Popular key-value databases#

Some of the popular key-value data stores used in the industry are Redis, Hazelcast, Riak, Voldemort, and Memcached.

When do I pick a key-value database?#

If you have a use case where you need to fetch data real fast with minimum fuss, you should pick a key-value datastore.

Key-value stores are built to serve use cases that require super-fast data fetch.

Typical use cases of a key-value database are:

• Caching
• Persisting user state
• Persisting user sessions
• Managing real-time data
• Implementing queues
• Creating leaderboards in online games and web apps
• Implementing a pub-sub system

Real-life implementations#

Here are some of the real-life implementations of the tech:

• Inovonics uses Redis to drive real-time analytics on millions of sensor data.
• Microsoft uses Redis to handle the traffic spike on its platforms
• Google Cloud uses Memcached to implement caching on their cloud platform.