Types

• Graph-oriented

  • The data models stored by graph databases are graph structures

  • A graph structure consists of nodes, edges and properties

  • Neo4j, FlockDB, OrientDB, …

• Document-oriented

  • Are designed to store data with the philosophy of storing a document

  • The data is arranged in the form of a book

    • A book can be divided into any number of chapters

    • Where each chapter can be divided into any number of topics

    • And each topic is further divided into sub-topics

    • And so on an so forth

  • Perfect option to store data that

    • Hierarchical tree-like structure

    • Does not have a fixed depth or schema

  • Have the indexes of keys stored in memory for faster searches

  • Data stored in the XML, JSON and other formats

  • Can hold scalar values, maps, lists and tuples

  • Every value stored in these datastore is always associated with a key

  • Schema-less

  • MongoDB, CouchDB, Elasticsearch …

• Column-oriented

  • Cassandra, Hadoop, HBase, …

• Key-value-oriented

  • One of the fastest and simplest NoSQL databases

  • A big hash table

  • Every value stored in the database has a key (for searching and deleting)

  • Redis, DynamoDB, …