Database Paradigm

Use the right tool for the job
Don't bring a knife to a gun fight

Key value DB (redis, memcache ... )

have sets of keys, where the keys are unique

• All data are held in machine memory, limits amount of data you can store however it make db very fast.
• Trade off - fast but limited space, No queries
• Best for - caching, pub/sub, leaderboards

Wide Column DB (Cassandra, Hbase ...)

Tradeoff : schema-less but without joins

• easy to scale up and replicate data across multiple nodes
• Best for - time series data, historical records, high write low read, records for IOT device ( water sensors), netflix ( histories of different shows you watch)

Document DB (Mongodb, firestore, dynamodb, couchdb ...)

• Tradeoff - schemaless, relationalish queries but without joins
• Best for - most apps, games, iot

Relationship DB (Mysql, postgresql ... )

Acid - Atomicity, consistency, isolation and durability, hard to scale, maybe try cockroach db

Graph DB

In graph you don't need middleman table

• Best for : graphs, knowledge graph, recommendation engine.

Search (elastic, algolia, meili search)

• best for - search engine, type ahead

Multi Model DB ( fauna DB, ArangoDB, OrientDB)

Multi-model database management systems unify multiple database systems into one. Instead of working with numerous models and finding ways to incorporate them together, multi-model databases provide a singular engine for various database types.