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From Apache Wiki <wikidi...@apache.org>
Subject [Couchdb Wiki] Update of "Introduction" by Linicks
Date Wed, 19 May 2010 21:08:59 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Couchdb Wiki" for change notification.

The "Introduction" page has been changed by Linicks.
The comment on this change is: Various improvements and addtions..
http://wiki.apache.org/couchdb/Introduction?action=diff&rev1=4&rev2=5

--------------------------------------------------

  = Introduction =
  <<TableOfContents()>>
  
+ == Meet CouchDB ==
+ CouchDB is often categorized as a “NoSQL” database, a term that has become increasingly
popular in late 2009, and early 2010.  While this is a rather generic, and sometimes offensive
characterization of a database, or data store, it does clearly define a break from traditional
SQL based databases.   CouchDB makes a clean break from the SQL database world in many ways.
 One of the primary differences  is  the lack of a schema,  or rigid pre-defined data structures
like tables.   Because the data stored in CouchDB is a JSON document(s), the structure of
the data, or document(s), can change dynamically.  This greatly simplifies the maintenance
and development of the database, especially over time when the data  and it's use evolve.
 Additionally, CouchDB doesn't rely on SQL JOINS to merge related data.  This is often confusing
for some users of traditional SQL databases, but is generally a non-issue once CouchDB users
become familiar it's powerful Map/Reduce framework.
  
- == Meet CouchDB  ==
+ CouchDB's departure from the SQL world isn't the only thing that makes CouchDB stand out
among a growing list of “NoSQL”  databases available.  One of CouchDB's most powerful
feature, is it's replication framework.  This replication framework provides a comprehensive
set of features:
  
- CouchDB is often categorized as a “NoSQL” database, a term that has become increasingly
popular in late 2009, and early 2010.  While this is a rather generic, and sometimes offensive
characterization of a database, or data store, it does clearly define a break from traditional
SQL based databases.   CouchDB makes a clean break from the SQL database world in many ways.
 One of the primary differences  is  the lack of a schema,  or rigid pre-defined data structures
like tables.   Because the data stored in CouchDB is a JSON document(s), the structure of
the data, or document(s), can change dynamically.  This greatly simplifies the maintenance
and development of the database, especially over time when the data  and it's use evolve.
 Additionally, CouchDB doesn't rely on SQL JOINS to merge related data.  This is often confusing
for some users of traditional SQL databases, but is generally a non-issue once CouchDB users
become familiar it's powerful Map/Reduce framework.  
+  * Master → Slave replication
+  * Master ↔ Maser replication
+  * Filtered Replication
+  * Incremental replication with bi-directional conflict detection/resolution
  
+ These replication features can be used in combination to create powerful solutions to many
problems in the IT industry, like reliability, and scalability. In addition to the fantastic
replication features, CouchDBs reliability and scalability is further enhanced by being implemented
in the Erlang programming language. Erlang has built-in support for concurrency, distribution,
fault tolerance, and has been used for years to build reliable systems in the telecommunications
industry. By design, the Erlang language and runtime are able to take advantage of newer hardware
with multiple CPU cores. When you look at all of the great characteristics of Erlang, it becomes
clear why CouchDB uses it for it's foundation.
- CouchDB's departure from the SQL world isn't the only thing that makes CouchDB stand out
among a growing list of “NoSQL”  databases available.  One of CouchDB's most powerful
feature, is it's replication framework.  This replication framework provides a comprehensive
set of features: 
-   * Master → Slave replication
-   * Master ↔ Maser replication
-   * Filtered Replication
-   * Incremental replication with bi-directional conflict detection/resolution
- These replication features can be used in combination to create powerful solutions to many
problems in the IT industry, like reliability, and scalability. 
  
  == What it is Not ==
-  * A relational database.
-  * A replacement for relational databases.
+ To better understand what CouchDB is, it may be helpful to understand a few things that
CouchDB isn't.
+ 
+  * A relational database.  These differences are articulated above in the Meet CouchDB section,
and other portions of this Wiki.
+  * A replacement for all databases.  When developing and designing a good information system
you should select the __best tool for the job__.  While CouchDB can be used in a wide variety
of application types including financial, you may find that a relational database, or other
data store is a better fit for your problem.  If you are new to CouchDB, and aren't sure if
it's a good fit for your data management problem, please ask others on the mailing list, and
the #couchdb IRC channel for advice.
-  * An object-oriented database. Or more specifically, meant to function as a seamless persistence
layer for an OO programming language.
+  * An object-oriented database.  While CouchDB stores JSON objects, it isn't meant to function
as a seamless persistence layer for an OO programming language.
  
  == Key Characteristics ==
+ 
+ Lets review some of the basic elements of CouchDB.  
+ 
  === Documents ===
  A CouchDB document is a [[http://www.json.org/|JSON]] object that consists of named fields.
Field values may be strings, numbers, dates, or even ordered lists and associative maps. An
example of a document would be a blog post:
  

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