Database Selection guide by March

- Key-value / Fast / Limited space / machine memory
-- Redis , Memcache , EdgeDb
--- Caching
--- Pub/sub
--- LeaderBoard

- Wide column (key value + more dimension) / Schema-less /without joins
-- Crasandra, Apache Hbase 
--- Time-series
--- Historical Records
--- High-write, Low-read

- Document (Collection of Doc, each doc contain key value pair) / Schema-less / Relational-ish Queries/ Without joins
-- MonoDB, file store db, dynamo db, couch db
--- Most Apps
--- Games
--- IOT
--- Not ideal for graph

- Relational (ACID) /Structured / Join able / Dificult to scale, see Cockroach labs
-- MYSQL, PostgreSQL, SQLServer
--- Most App
--- Not ideal for unstructured data

- Graph (structured without middleman table to joins) / Connected / good for joins
-- Neo4J , DGraph
--- Graphs
--- Knowledge Graphs
--- Recommendation Engine
--- Great alternative to Structured db especially if we use much more joins

- Search (Full text index, similar to document based but they analyze all the text)
-- Elasticsearch, Solr, Meilisearch
--- Search engines
--- TypeAHead

- Multi-model (Can ignore about the background engine and focus on JSON result)
-- Fauna DB
--- Everythings !

- Hornorable mention
- Data warehouse
- Time Series