learn-coucdb

Quick Start to learning CouchDB

What is Apache CouchDB?

1. open source database software
2. focuses on ease of use
3. an architecture that "completely embraces the Web".
4. has a document-oriented NoSQL database architecture
5. implemented in the concurrency-oriented language Erlang;
6. it uses JSON to store data,
7. JavaScript as its query language using MapReduce, and HTTP for an API.

Overview about NoSql Dbs:

NoSQL [not only SQL] is a movement towards document stores that do not make use of the relational model.

The primary objective of a NoSQL database is to have the following −

• Simplicity of design,
• Horizontal scaling, and
• Finer control over availability.

NoSql DBs:

Three types:

Key-val Store	Column Store	Document Store
Data stores as K,V pairs	Grouped by columns of data	Based on (K,V) store, where documents contain complex data
No Schema	Columns further grouped into column families	Each doc is assigned a unique key used to retrieve any document.
Each data - (Index key, corresponding val)	Column families contain any number of columns	designed for storing, retrieving, and managing document-oriented information
Cassandra, DynamoDB, BerkleyDB	BigTable,HBase,HyperTable	CouchDB, MongoDB

Installation

On Ubuntu:

######Steps:

1: sudo apt-get update

2: Install the software to manage the source repos:

   `sudo apt-get install software-properties-common -y`

3: Add the PPA that will help fetch the latest CouchDB version:

    `sudo add-apt-repository ppa:couchdb/stable -y`

4: Post adding PPA, update the system for latest package:

    `sudo apt-get update`

5: Remove the existing version if any previous version exist :

    `sudo apt-get remove couchdb couchdb-bin couchdb-common -yf`

6: Install CouchDB:

    `sudo apt-get install couchdb -y`

By default, CouchDB runs on localhost and uses the port 5984. You can retrieve this basic information by running curl from the command line:

`curl localhost:5984`

Futon

Futon is the built-in, web based, administration interface of CouchDB.

Databases:

1. Creates databases
2. Destroys databases

Documents:

1. Creates documents
2. Updates documents
3. Edits documents
4. Deletes documents

Starting Futon: http://localhost:5984/_utils/

You can perform various DB operation from your terminal using cURL utility as follows: -> The below operations can be also performed from the web based interface easily.

curl localhost:5984 {"couchdb":"Welcome","uuid":"74e8f212283cce22b69c98104329d4ea","version":"1.6.1","vendor":{"name":"Ubuntu","version":"14.04"}}

List all DBs:

curl -X GET http://localhost:5984/_all_dbs

Output:

["_replicator","_users"]

Creating a DB:

curl -X PUT localhost:5984/mydb

Output:

{"ok":true}

Get Db info:

curl -X GET localhost:5984/mydb

Output:

{"db_name":"mydb","doc_count":0,"doc_del_count":0,"update_seq":0,"purge_seq":0,"compact_running":false,"disk_size":79,"data_size":0,"instance_start_time":"1484565759558185","disk_format_version":6,"committed_update_seq":0}

Deleting a DB:

List all DBs:

curl -X GET localhost:5984/_all_dbs

Output:

["_replicator","_users","mydb","mydb1"]

Delete a DB:

curl -X DELETE localhost:5984/mydb1

Output:

{"ok":true}

Verify if deleted:

curl -X GET localhost:5984/_all_dbs

Output: ["_replicator","_users","mydb"]

Creating a Document:

curl -X PUT http://localhost:5984/mydb/"111" -d '{"Name":"Surabhi", "Email":"surabhi@gmail.com", "age":"22" }'

Output:

{"ok":true,"id":"111","rev":"1-703389496da6dbc37bbb56f16bb6ac4c"}

"rev", this indicates the revision id. Every time you revise (update or modify) a document a _rev value will be generated by CouchDB. If you want to update or delete a document, CouchDB expects you to include the _rev field of the revision you wish to change. When CouchDB accepts the change, it will generate a new revision number. This mechanism ensures concurrency control.

Verify if the Document is created:

curl -X GET localhost:5984/mydb/111

Output:

{"_id":"111","_rev":"1-703389496da6dbc37bbb56f16bb6ac4c","Name":"Surabhi","Email":"surabhi@gmail.com","age":"22"}

Updating Document

curl -X PUT localhost:5984/mydb/111 -d '{"Name":"Surabhi Borgikar", "_rev":"1-703389496da6dbc37bbb56f16bb6ac4c"}'

Output:

{"ok":true,"id":"111","rev":"2-33b45809b4a69edb71fc908e1f9956df"}

Verify:

curl -X GET localhost:5984/mydb/111 {"_id":"111","_rev":"2-33b45809b4a69edb71fc908e1f9956df","Name":"Surabhi Borgikar"}

Adding a new field to an existing document is not allowed in CouchDB. Instead, a new document using the revision number of previous is created with and a new version number assigned to new(updated) document. The revision number is passed as part of the Json request from cURL.

Useful links (referred the following for documenting this):

https://code.tutsplus.com/articles/getting-started-with-couchdb--net-18801

http://guide.couchdb.org/editions/1/en/index.html

https://www.tutorialspoint.com/couchdb/index.htm