CouchDB

After installing CouchDB, the container is ready to enter the downloaded application in a few steps.

The last statement in Listing 2 defines the URL that you'll use to access the CouchDB database used for the article's examples.

In this article, I'll introduce you to CouchDB and show you how you can rapidly get up to speed with using it.

All data in a CouchDB database is stored in a document, and each document can be made up of an undefined number of fields.

CouchDB can be a great alternative to relational databases for many applications, especially ones involving less-structured data.

CouchDB is schemaless in that each document stands on its own and requires no specific fields (other than an identifier and a revision).

With CouchDB, you can search for documents, properties of documents, and even relate documents just as in the relational world.

As you can see, CouchDB has tried to create the database, but encountered an error in the process.

Don't try to use CouchDB in a relational way, like inserting ID fields that help you make relationships clear between documents.

Listing 1 is an example of the map and reduce functions of a CouchDB view that counts the number of documents that have an attachment.

Now, try listing all the collections set up in CouchDB.

CouchDB databases store uniquely named documents and provide a RESTful JSON API that allow applications to read and modify these documents.

In a recent article I showed you how a document-oriented datastore (CouchDB) differs vastly from schema-oriented relational databases.

CouchDB does not allow you to create the same database twice.

This simple API call is a simple GET request, with the response informing us of the version of CouchDB installed.

Views in CouchDB are created on demand and can be used to aggregate, join, and report on documents in the database.

CouchDB can scale to many instances and incrementally replicate between the various nodes in the cluster.

This is all built on top of CouchDB replication abilities, which I have found useful even outside of scaling distributed CouchDB databases.

Some knowledge of how CouchDB stores these results is necessary to understand this reduce function.

Now that I've created a few parking tickets (or documents in CouchDB speak), it's time to create a view in CouchDB.

CouchDB views can be permanent views stored inside design document, or temporary views executed on demand.

Next month, I'll give you a look at CouchDB, a document-oriented database that's is distinctly different from, say, MySQL.

Apache CouchDB is an open source document-oriented database management system that stores data as JSON objects.

CouchDB will not let you update a document if your revision number is out of date.

CouchDB does not come with an auto-increment or sequence feature.

If you don't see this message, go back through your installation and configuration process to get CouchDB up and running.

Installation of CouchDB varies depending on your operating system.

In the URL, substitute the correct port number if your CouchDB installation is not configured to use the default port.

These plugins include accessing various data stores including CouchDB, REST storage and Google AppEngine.

The target CouchDB can be an existing remote or local database.

This article covers the use of Clojure for performing basic CouchDB operations, querying CouchDB using views, and database replication.

The process is operated by entering the URL of the source and target CouchDB and activating the Replicate button.

From the Terminal window, run the following command to retrieve any last-minute changes or dependencies: sudo port upgrade couchdb.

All it does is filter the documents in the CouchDB database by a document's officer property.

You need to install CouchDB from source if you want the very latest version (see Resources).

Specifically, your CouchDB instance has one database in it: songs.

The easiest way is to use CouchDB's Futon application (see Resources).

CouchDB replication occurs between two existing (local or remote) databases.

In this article you learned about the technical viewpoint for offline applications with CouchDB.

These views actually are stored as regular CouchDB documents but with special names.

CouchDB's emit function works as an organizer of sorts.

The approached will be discussed at the CouchDB community meeting this week.

Also, the same rule as in the Updating a CouchDB document section applies here.

CouchDB can be installed from source or, where available, it can be installed using a package manager (e. g. , MacPorts on Mac OS X).

Apache CouchDB, a new (at release 0. 10. 0 as of this writing) open source database, is no exception.

This revision is actually the MD5 hash of the document, automatically added by CouchDB.

Change the port number as needed in your REPL session if your copy of CouchDB is configured differently.

CouchDB was originally written in C , but in April 2008, the project moved to the Erlang OTP platform for its emphasis on fault tolerance.

CouchDB does not feature locking mechanisms; two clients can load and edit the same document at the same time.

Here's something else that CouchDB isn't: an object-oriented database.

The primary tool for querying and reporting CouchDB is views.

First, when issuing a PUT for a CouchDB document, you must assign a UUID.

Replicating data in CouchDB is a one-step process from an API perspective.

CouchDB makes this easy by giving you the ability to replicate at a database level using the same REST interface you've been using thus far.

The ability to write CouchDB views in Clojure means you have one less language to support in an application and more continuity in the code.

Now you have a design document where the CouchDB application can be stored.

This launches the CouchDB server and keeps it running persistently, so it will start up if you ever restart your Mac.

To simplify matters, create a new database in the same CouchDB node (for example, new-stuff-db).

In the Creating a CouchDB document section, you created a record for the movie Psycho.

Listing 4 is a JSON document (from CouchDB) followed by an equivalent Clojure map representation

Views: Getting useful information out of CouchDB

Listing 4 creates another parking ticket in CouchDB via the same technique