Document-oriented database

A document-oriented database is a computer program designed for storing, retrieving, and managing document-oriented information, also known as semi-structured data. Document-oriented databases are one of the main categories of so-called NoSQL databases and the popularity of the term "document-oriented database" (or "document store") has grown^{[citation needed]} with the use of the term NoSQL itself. In contrast to well-known relational databases and their notions of "Relations" (or "Tables"), these systems are designed around an abstract notion of a "Document".

Documents

The central concept of a document-oriented database is the notion of a Document. While each document-oriented database implementation differs on the details of this definition, in general, they all assume documents encapsulate and encode data (or information) in some standard formats or encodings. Encodings in use include XML, YAML, JSON, and BSON, as well as binary forms like PDF and Microsoft Office documents (MS Word, Excel, and so on).

Documents inside a document-oriented database are similar, in some ways, to records or rows in relational databases, but they are less rigid. They are not required to adhere to a standard schema, nor will they have all the same sections, slots, parts, or keys. For example, the following is a document:

  {
     FirstName:"Bob",
     Address:"5 Oak St.",
     Hobby:"sailing"
  }

A second document might be:

  {
      FirstName:"Jonathan",
      Address:"15 Wanamassa Point Road",
      Children:[
         {Name:"Michael",Age:10},
         {Name:"Jennifer", Age:8},
         {Name:"Samantha", Age:5},
         {Name:"Elena", Age:2}
    ]
   }

These two documents share some structural elements with one another, but each also has unique elements. Unlike a relational database where every record contains the same fields, leaving unused fields empty; there are no empty 'fields' in either document (record) in the above example. This approach allows new information to be added to some records without requiring that every other record in the database shares the same structure.

Keys

Documents are addressed in the database via a unique key that represents that document. This key is often a simple string, a URI, or a path. The key can be used to retrieve the document from the database. Typically, the database retains an index on the key to speed up document retrieval.

Retrieval

Another defining characteristic of a document-oriented database is that, beyond the simple key-document (or key-value) lookup that can be used to retrieve a document, the database offers an API or query language that allows the user to retrieve documents based on their content. For example, you may want a query that retrieves all the documents with a certain field set to a certain value. The set of query APIs or query language features available, as well as the expected performance of the queries, varies significantly from one implementation to the next.

Organization

Implementations offer a variety of ways of organizing documents, including notions of

• Collections
• Tags
• Non-visible Metadata
• Directory hierarchies
• Buckets

Implementations

Name	Publisher	License	Language	Notes	RESTful API
BaseX	BaseX Team	BSD License	Java, XQuery	Support for XML, JSON and binary formats; client-/server based architecture; concurrent structural and full-text searches and updates; REST APIs.	Yes
ArangoDB	triAGENS	Apache 2 License	C, C++ & Javascript	A multi model, high-performance document store and graph database.	Yes
Cloudant	Cloudant, Inc.	Proprietary	Erlang, Java, Scala, and C	Distributed database service based on BigCouch, the company's open source fork of the Apache-backed CouchDB project.	Yes
Clusterpoint	Clusterpoint Ltd.	Free community license / Commercial	C++	Schema-free, document-oriented database management system platform with server based data storage, full text search engine functionality, information ranking for search relevance and clustering.	Yes
Couchbase Server	Couchbase, Inc.	Apache License	Erlang and C	Distributed NoSQL Document Database.	Yes
CouchDB	Apache Software Foundation	Apache License	Erlang	JSON over REST/HTTP with Multi-Version Concurrency Control and limited ACID properties. Uses map and reduce for views and queries.	Yes
eXist	eXist, [3]	GPL	XQuery, Java	XML over REST/HTTP, WebDAV, Lucene Fulltext search, validation, versioning, clustering, triggers, URL rewriting, collections, ACLS, XQuery Update	Yes
FleetDB	FleetDB	MIT License	Clojure	A JSON-based schema-free database optimized for agile development.	(unknown)
Jackrabbit	Apache Software Foundation	Apache License	Java		(unknown)
Lotus Notes	IBM	Proprietary	LotusScript, Java, Lotus @Formula		(unknown)
MarkLogic	MarkLogic Corporation	Free Express license or Commercial	REST, Java, XQuery, XSLT, C++	Distributed document-oriented database with Multi-Version Concurrency Control, integrated Full text search and ACID-compliant transaction semantics	Yes
MongoDB	10gen, Inc	GNU AGPL v3.0	C++	Document-oriented database optimized for highly transient data	Optional
MUMPS Database		Proprietary and GNU Affero GPL	MUMPS	Commonly used in health applications.	(unknown)
OrientDB	Orient Technologies	Apache License	Java	JSON over HTTP	Yes
Apache Cassandra	Apache Software Foundation	Apache License	Java	JSON over HTTP	Yes
Redis		BSD License	ANSI C	Key-value store supporting lists and sets with binary-safe protocol	(unknown)
Rocket U2	Rocket Software	Proprietary		UniData, UniVerse	Yes (Beta)

XML database implementations

Further information: XML database

Most XML databases are document-oriented databases.

See also

• Internet Message Access Protocol (IMAP)
• Database theory
• In-memory database
• NoSQL
• Object database
• Online database
• Real time database
• Relational database
• Data hierarchy

Further reading

• Assaf Arkin. (2007, September 20). Read Consistency: Dumb Databases, Smart Services. Labnotes:Don’t let the bubble go to your head!

External links

• http://solprovider.com/articles/20020612&cat=Lotus/IBM