NoSQL databases refer to any database types that are not only relational. “NoSQL” stands for “not only SQL”.
Relational database is the most popular database type nowadays. Structure Query Language (SQL) is a language to manage data in a relational database. This is why NoSQL is the term used to referred to not only relational databases.
Types of NoSQL Databases
Types of NoSQL Databases:
- Key-value stores
- Document stores
- Graph databases
- Wide-column stores
- Search stores
- Object-oriented stores
- Multi-model stores
Key-value stores are key/value pairs.
Document stores are similar to key/value stores, but the value is much more complex and it is in the form of a document, like XML or JSON
Graph databases store data in graph format.
Wide-column stores are optimized for queries over large datasets, and instead of rows, they store columns of data together.
NoSQL Databases Solutions
No SQL databases solutions:
- Key-value stores
- Valkey
- Redis
- Amazon Dynamo DB
- Etcd
- Riak
- Document stores
- Apache Couchbase
- FerretDB
- MongoDB
- Firebase
- Wide-column stores
- Apache Cassandra
- Apache HBase
- Bigtable
- Apache Druid
- Hypertable
- Graph store
- JanusGraph
- Neo4j
- Amazon Neptune
- Search
- ElasticSearch
- Algolia
- Mellisearch
- Multi-model
- Azure Cosmo DB
- ArangoDB
Take into account that traditionally relational DB PostgreSQL also accepts some of these models.
Key-value Store Solutions
The most popular key-value databases are Valkey, Redis and Amazon DynamoDB.
You can read more about key-value store solutions on this post.
Document Store Solutions
Document stores are specifically designed to handle JSON-like documents.
Some of the most popular document store databases are Apache CouchDB and MongoDB.
You can read more about document store solutions on this post.
Wide-column Store Solutions
A wide-column uses a partition key and a clustering key.
Wide-column store solutions:
- Apache Cassandra
- Apache HBase
- Bigtable
- Apache Druid
- Hypertable
Apache Cassandra
Apache Cassandra is a distributed wide-column store.
It considers pairs of column name/key and column value that are organized in column families (CFs). The aggregation of column families forms a keyspace.
It uses the JSON format.
It is free and open source software (FOSS) under an Apache 2.0 license.
Apache Cassandra official website
Apache HBase
Apache HBase is a single-server wide-column store based on Bigtable.DH
Apache HBase is built on top of the distributed file system Hadoop File System (HDFS).
It is FOSS under an Apache 2.0 license.
Bigtable
Bigtable is a wide-column store.
As part of the Google Cloud portfolio, it is developed by the American company Google.
Apache Druid
Apache Druid is FOSS under an Apache 2.0 license.
Hypertable
Graph Store Solutions
Graph store solutions:
- JanusGraph
- Neo4j
- Amazon Neptune
- ArangoDB
- DGraph
- Infinite Graph
- AllegroGraph
- DEX/Sparksee
- Sones GraphDB
- InfoGrid
- HyperGraphDB
The most relevant are Neo4j and JanusGraph.
JanusGraph
JanusGraph is developed by The Linux Foundation.
It is FOSS under an Apache 2.0 license.
Neo4j
Neo4j is a graph store database.
It is source-viewable software under a GPLv3 license with a Commons Clause.
Amazon Neptune
Amazon Neptune is a graph store database.
Amazon Neptune official website
ArangoDB
ArangoDB is a graph store database.
It is source-viewable under a BSL (Business Source License) 1.1.
DGraph
DGraph.
InfiniteGraph
InfiniteGraph
Search
- OpenSearch
- ElasticSearch
- Algolia
- Mellisearch
Object-oriented
Object-oriented database (OODB) is a database paradigm.
Mandatory characteristics of a OODB:
- All objects have a unique identifier, independent to their attributes.
- It allows building complex objects.
- The BBDD schema includes a limited set of classes or types.
- The data type are variable.
Object-oriented databases featured on this post:
- db4o (discontinued but historically significant)
- ObjectDB
- Versant Object Database
Multi-model
- OrientDB
- Azure Cosmos DB
- FaunaDB
- Couchbase Server
OrientDB
OrientDB is a multi-model database that combines the features of graph databases and document databases. It supports SQL-like queries, graph traversals, and ACID transactions.
Azure Cosmos DB
Azure Cosmos DB offers all types of NoSQL store.
Azure Cosmos DB official website
FaunaDB
FaunaDB
Couchbase Server
The community edition is released under an Apache 2.0.
Do not confuse it with document-based store CouchDB.
You might also be interested in…
External references
- “CISSP Offical Study Guide: 9th Edition”, pp. 983; Chapple et al; Wiley, 2021.
- Reddit community; “Alternative to MongoDB“; Reddit, 2022
- Redis
- Quora community; “Is Redis a NoSQL database?“; Quora
- MongoDB
- Reddit community; “Looking for active fork of MongoDB under AGPL“; Reddit, 2019
- Reddit community; “Has SSPL-licensed MongoDB been accepted?“; Reddit, 2024