couchdb-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Apache Wiki <wikidi...@apache.org>
Subject [Couchdb Wiki] Trivial Update of "Introduction" by TiffanyConroy
Date Sun, 07 Nov 2010 11:40:20 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 TiffanyConroy.
The comment on this change is: Minor grammar fixes.
http://wiki.apache.org/couchdb/Introduction?action=diff&rev1=6&rev2=7

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

  <<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.
+ CouchDB is often categorized as a “NoSQL” database, a term that became increasingly
popular in late 2009, and early 2010.  While this term 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 feature greatly simplifies
the maintenance and development of the database, especially over time when the data and its
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 its powerful Map/Reduce framework.
  
- CouchDB's departure from the SQL world isn't the only thing that makes CouchDB stand out
among a growing list of “NoSQL”  databases.  One of CouchDB's most powerful feature, is
it's replication framework.  This replication framework provides a comprehensive set of features:
+ CouchDB's departure from the SQL world isn't the only thing that makes CouchDB stand out
among a growing list of “NoSQL” databases.  One of CouchDB's most powerful feature, is
its 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. 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.
+ 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, CouchDB's 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 its foundation.
  
  == What it is Not ==
  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.
+  * 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.  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.  
+ Let's 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:
@@ -43, +43 @@

  A CouchDB database is a flat collection of these documents. Each document is identified
by a unique ID.
  
  === Views ===
- To address this problem of adding structure back to semi-structured data, CouchDB integrates
a view model using Javascript for description. Views are the method of aggregating and reporting
on the documents in a database, and are built on-demand to aggregate, join and report on database
documents. Views are built dynamically and don’t affect the underlying document, you can
have as many different view representations of the same data as you like.
+ To address this problem of adding structure back to semi-structured data, CouchDB integrates
a view model using JavaScript for description. Views are the method of aggregating and reporting
on the documents in a database, and are built on-demand to aggregate, join and report on database
documents. Views are built dynamically and don’t affect the underlying document; you can
have as many different view representations of the same data as you like.
  
  === Schema-Free ===
  Unlike SQL databases which are designed to store and report on highly structured, interrelated
data, CouchDB is designed to store and report on large amounts of semi-structured, document
oriented data. CouchDB greatly simplifies the development of document oriented applications,
which make up the bulk of collaborative web applications.
  
  In an SQL database, as needs evolve the schema and storage of the existing data must be
updated. This often causes problems as new needs arise that simply weren't anticipated in
the initial database designs, and makes distributed  "upgrades" a problem for every host that
needs to go through a schema update.
  
- With CouchDB, no schema is enforced, so new document types with new meaning can be safely
added alongside the old. The view engine, using Javascript, is designed to easily handle new
document types and disparate but similar  documents.
+ With CouchDB, no schema is enforced, so new document types with new meaning can be safely
added alongside the old. The view engine, using JavaScript, is designed to easily handle new
document types and disparate but similar  documents.
  
  === Distributed ===
  CouchDB is a peer based distributed database system. Any number of CouchDB hosts (servers
and offline-clients) can have independent "replica copies" of the same database, where applications
have full database interactivity (query, add, edit, delete). When back online or on a schedule,
database changes are replicated bi-directionally.

Mime
View raw message