Tag Archives: MongoDB

05 Apr

In the world of NoSQL-Hands on Mongodb-1

I’m hearing a lot of “NoSQL” these days. To really understand how (and) does it works, I decided to give a try on MongoDB.

MongoDB (hu*mongo*us) is an open source, scalable, high-performance, schema-free, document-oriented database written in the C++ programming language.

MongoDB is not a Relational Database Management System. The database manages collections of JSON (JavaScript Object Notation)-like documents which are stored in a binary format referred to as BSON (Binary JSON).

This post will surely get you started with the MongoDB-NoSQL.

Installing MongoDB:

  • Download Mongodb from www.mongodb.org
  • Extract binaries
  • Create data directory – default for windows C:\data\db
  • Install service:¬†Full\path\to\mongod.exe –install

If you want to change default data directory location:
Full\path\to\mongod.exe –dbpath=”\”full\path\to\”” –install

Troubleshooting Mongodb Installtion Error:
I faced while installing, if you get error like:
shutdown: going to close listening sockets.
shutdown: going to flush oplog…
shutdown: going to close sockets…
shutdown: waiting for fs preallocator…
shutdown: closing all files…
closeAllFiles() finished
dbexit: really exiting now

Go to: HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/
Check for MongoDB
Verify the value of ImagePath is proper

This seems to be caused by not giving full-path while installing.

Add Environment variable Path, add path/upto/mongo-bin-dir;

Okay, now we’re all set to checkout the MongoDB-NoSQL world.

MongoDB GUI Administration Tool:

There is a GUI Admin tool available phpmoadmin to simplify the MongoDB Operations.
Signle php script: phpmoadmin
Download PHP extension from php.net/manual/en/mongo.installation.php
Extract in ext directory of WAMP & Restart.

In case of error you may install Microsoft Visual C++ 2008 SP1 Redistributable Package (x86) [www.microsoft.com/downloads/details.aspx?familyid=A5C84275-3B97-4AB7-A40D-3802B2AF5FC2&displaylang=en]

MySQL to MongoDB Database Migration:

Create CSV from MySQL:
Query OK, 293911 rows affected (1 min 8.17 sec)

Import CSV to mongodb using mongoimport:
C:\>mongoimport -d DATABASENAME -c TABLENAME –file “c:\TABLENAME.csv” –type csv -f FIELD1,FIELD2…

Using MongoDB on Windows:

On Command Prompt:
MongoDB shell version: 1.4.0
url: test
connecting to: test
type “exit” to exit
type “help” for help

By default it’s connecting to test database.
Default mongodb port is 9999.

Basic Commands

  • show dbs : show database names
  • show collections : show collections in current database
  • show users : show users in current database
  • show profile : show most recent system.profile entries with time >= 1ms
  • use : set curent database to
  • db.help() : help on DB methods
  • db.foo.help() : help on collection methods
  • db.foo.find() : list objects in collection foo
  • db.foo.find( { a : 1 } ) : list objects in foo where a == 1 it result of the last line evaluated; use to further iterate

Simple Queries with MongoDB:

Set Current Database:

See Present Database:
> db

View collections (tables) under present db:
> db.getCollectionNames()
[ “TABLENAME”, “system.indexes” ]

SQL>Select count(*) from TABLENAME:
NoSQL> db.TABLENAME.count()

SQL>select * from TABLENAME where field1 regexp ‘enrique’:
NoSQL>db.TABLENAME.find( { field1 : /enriqu/i} );

For simple find:
NoSQL>db.TABLENAME.find( { field1 : “value” } );

SQL>Select field1 from table where field2=”%search%”:
NoSQL>db.TABLENAME.find( { field2 : /search/i} , {field1 : 1 } );

SQL>Select All but one (field1) column:
NoSQL>db.TABLENAME.find( { field2 : /search/i} , {field1 : 0 } );

SQL>Select with sort order ascending and descending (1,-1):
NoSQL>db.TABLENAME.find( { ar_name : /enrique/i }, {field1 : 1 } ).sort({ field1 : -1})

MongoDB now seems easy to follow, but I’m still having hard time in taking on the Map/Reduce.
More in the next post; ofcourse documentation home is a good place, else you may export the pdf / html / xml documentation here.

-- Kedar Vaijanapurkar --