CouchDB.tex

\chapter{CouchDB}
\label{chap:CouchDB}

CouchDB is a new, open-source NoSQL database system. The data is stored in JSON
format. To query the data, JavaScript is the query language using MapReduce,
HTTP protocol. Unlike MongoDB which has only one master node, CouchDB has
multi-master replication.  The master node contains document metadata.
Document metadata contains revision information, making it possible to merge any
differences that may have occurred while the databases were disconnected.
Multi-version Concurrency Control (MVCC) is used in CouchDB, which avoid locking
the database file during writes. Thus, conflicts are left to the application to
resolve.

CouchDB was first released in 2005, and become Apache first level project in
2008.

CouchDB use document-like architecture, i.e. each database is a collection of
independent documents. Each document maintains its own data and self-contained
schema.


As a distributed database system, one can be stored on the phone and one on the
server. An application can access CouchDB data from multiple databases.

\url{http://en.wikipedia.org/wiki/CouchDB}