MongoDB Database

MongoDB is document-oriented database management system designed for modern web applications and internet infrastructures. It scales easily and capable to store rich data structures. In this, data objects are stored inside a collection and database contains a set of different collections.

These are the some useful database related commands -

Login for Database Authentication

Before using the database, the user is required to authenticate using valid database credentials. Here is the command used for authentication.

db.auth("username", "password");

Show Databases

MongoDB show command is used to show all the current existing databases on MongoDB server.

show dbs;

By default, mongodb has three existing databases.

• admin - This is the root database. There are certain server side commands that permit to run on admin database only. If a user has permission to access admin database, then that user automatically gain permission to run all databases.
• local - This is used to store any collections that are local to a server. We cannot replicate this database.
• config - This is basically used in sharding to store information about the shards.

Create MongoDB Database

If you are familiar with relational database, it provides CREATE statement to create a new database and define structure. But there is no such CREATE command in MongoDB. The use command is used to create a new database or to choose the existing database for operation. If it does not exist, then it will create a database of the specified name. There is no need to define structure of database like RDBMS. This makes the MongoDB more dynamic and flexible.

Syntax of Create Database

use DATABASE_NAME;

Example

use school;

The mongodb database contains group of collections. The database name can be -

• Any UTF-8 string except these characters (/, \, ., ", *, <, >, :, |, ?, $, \0).
• It is basically sticks with alphanumeric ASCII.
• The database names are limited to a maximum of 64 bytes.

Current Database

To know the name of current using database, simply write db command.

db;

Show Collections

The mongodb show collections command returns list of all collections created in the current database.

show collections;

Drop Database

The dropDatabase() command is used to drop the current database. Before using this command, first we need to select database using 'use' command.

Example

>db.dropDatabase()
{ "dropped" : "school", "ok" : 1 }

Backup Database

The mongodump utility is used for backing up database, by creating a binary export of database content.

>mongodump -h localhost --port 27017

Restore Database

The mongorestore utility is used for restoring data in database either from a binary database dump created by mongodump or from the standard input.

>mongorestore -h localhost --port 27017 dump

MongoDB Database Statistics

We can know about database statistics using stats() command. This is helpful in complicated debugging.

> db.stats();
{
        "db" : "school",
        "collections" : 3,
        "views" : 0,
        "objects" : 7,
        "avgObjSize" : 65.71428571428571,
        "dataSize" : 460,
        "storageSize" : 69632,
        "numExtents" : 0,
        "indexes" : 3,
        "indexSize" : 69632,
        "fsUsedSize" : 85098131456,
        "fsTotalSize" : 630906155008,
        "ok" : 1
}
>