Apache CouchDB

Apache CouchDB was initially developed at IBM and donated later on to the Apache Software Foundation.

Compared to other databases around, CouchDB is still very young, but this has not stopped it from gathering quite a following in its short lifespan.

The CouchDB engine has been at the forefront of the recent wave of NoSQL systems, database engines that use a key-value model to store their data in local JSON documents.

Recorded data can still be queried but not with a classic SQL syntax. Instead a special syntax is used, in CouchDB's case via a custom query language executed via JavaScript.

The database itself has been quite a success, even before reaching Apache's portfolio, and is currently in use at companies like the BBC, Ubuntu, Engine Yard and Credit Suisse.

This release leads to the Apache CouchDB source code download. For the binary please refer to the Mac and Windows sections.

Features:

• Document database server
• Accessible via a RESTful JSON API.
• Ad-hoc and schema-free
• A flat address space
• Provides ACID semantics
• Eventual consistency
• Offline mode support
• Support for distributed architectures
• Easy data replication
• Bi-directional conflict detection
• Can be queried and indexed via JavaScript

What is new in this release:

• Support Erlang/OTP 17.0
• Many improvements in our experimental new user interface, including switching the code editor from CodeMirror to Ace as well as better support for various browsers.
• Added the max_count option (UUIDs Configuration) to allow rate-limiting the amount of UUIDs that can be requested from the /_uuids handler in a single request.
• Increased socket buffer size to improve replication speed for large documents and attachments, and fix tests on BSD-like systems.
• Improve performance of multipart/related requests.
• Verify that authentication-related configuration settings are well-formed.
• Fixed CORS exposed headers.
• Renamed proxy_authentification_handler to proxy_authentication_handler.
• Ensure the startup script clears the pid file on termination.

What is new in version 1.5.0:

• Fixed an issue where admin users would be restricted by the public_fields feature.
• Fixed an issue with the JavaScript CLI test runner.
• The official documentation has been overhauled. A lot of content from other sources have been merged, and the index page has been rebuilt to make the docs much more accessible.
• A new administration UI, codenamed Fauxton, has been included as an experimental preview. It can be accessed at /_utils/fauxton/. There are too many improvements here to list them all. We are looking for feedback from the community on this preview release.

What is new in version 1.4.0:

• Now supports Erlang/OTP R16B and R16B01; the minimum required version is R14B.
• User document role values must now be strings. Other types of values will be refused when saving the user document.

What is new in version 1.3.0:

• No longer rewrites the X-CouchDB-Requested-Path during recursive calls to the rewriter.
• Limit recursion depth in the URL rewriter. Defaults to a maximum of 100 invocations but is configurable.
• Fix _session for IE7.
• Added Server-Sent Events protocol to db changes API.
• Added view request duration to Futon.
• Disable buttons for actions that the user doesn't have permissions to.
• C/C++ compiler detection has been improved.
• Database name is encoded during rewriting (allowing embedded /'s, etc).

What is new in version 1.2.2:

• Reset rewrite counter on new request, avoiding unnecessary request failures due to bogus rewrite limit reports.
• Fixed issue in CouchDB script where stopped status returns before process exits.

What is new in version 1.2.1:

• Fixed various bugs in the URL rewriter when recursion is involved.
• Fixed couchdb start script.
• Disabled buttons that aren't available for the logged-in user.
• Fixed potential replication timeouts.

What is new in version 1.2:

• Added a native JSON parser
• Optional file compression (database and view index files)
• Several performance improvements, especially regarding database writes and view indexing
• Performance improvements for the built-in changes feed filters _doc_ids and _design

What is new in version 1.1.1:

• Support SpiderMonkey 1.8.5
• Add configurable maximum to the number of bytes returned by _log.
• Allow CommonJS modules to be an empty string.
• Bump minimum Erlang version to R13B02.
• Do not run deleted validate_doc_update functions.
• ETags for views include current sequence if include_docs=true.
• Fix bug where duplicates can appear in _changes feed.
• Fix bug where update handlers break after conflict resolution.
• Fix bug with _replicator where include "filter" could crash couch.
• Fix crashes when compacting large views.
• Fix file descriptor leak in _log
• Fix missing revisions in _changes?style=all_docs.
• Improve handling of compaction at max_dbs_open limit.
• JSONP responses now send "text/javascript" for Content-Type.
• Link to ICU 4.2 on Windows.
• Permit forward slashes in path to update functions.
• Reap couchjs processes that hit reduce_overflow error.
• Status code can be specified in update handlers.
• Support provides() in show functions.
• _view_cleanup when ddoc has no views now removes all index files.
• max_replication_retry_count now supports "infinity".
• Fix replication crash when source database has a document with empty ID.
• Fix deadlock when assigning couchjs processes to serve requests.
• Fixes to the document multipart PUT API.
• Fixes regarding file descriptor leaks for databases with views.

What is new in version 1.1.0:

• Native SSL support.
• Added support for HTTP range requests for attachments.
• Added built-in filters for `_changes`: `_doc_ids` and `_design`.
• Added configuration option for TCP_NODELAY aka "Nagle".
• Allow wildcards in vhosts definitions.
• More granular ETag support for views.
• More flexible URL rewriter.
• Added OS Process module to manage daemons outside of CouchDB.
• Added HTTP Proxy handler for more scalable externals.
• Added `_replicator` database to manage replications.
• Multiple micro-optimizations when reading data.
• Added CommonJS support to map functions.
• Added `stale=update_after` query option that triggers a view update after returning a `stale=ok` response.
• More explicit error messages when it's not possible to access a file due to lack of permissions.
• Added a "change password"-feature to Futon.

Limitations:

• It is not:
• A relational database.
• A replacement for relational databases.
• An object-oriented database.