How to use the command "mongodump" (with examples)

The “mongodump” command is a utility provided by MongoDB that allows you to export the contents of a MongoDB instance. It can be used to create dumps of databases or specific collections, and supports various options to customize the backup process.

Use case 1: Create a dump of all databases

Code:

mongodump

Motivation: One common use case for mongodump is creating a backup of all the databases in your MongoDB instance. This is useful for situations like migrating data to a different server or recovering from data loss. By running the mongodump command without any additional arguments, it will create a dump of all the databases and place the dump files inside a directory called “dump”.

Explanation: The command mongodump without any arguments will create a dump of all the databases in the MongoDB instance. It will connect to the default host and port (localhost:27017) and create a directory named “dump” in the current working directory. Inside the “dump” directory, separate subdirectories will be created for each database, containing the dump files.

Example output: The command will generate a directory structure as follows:

dump/
   database1/
      collection1.bson
      collection2.bson
   database2/
      collection3.bson

Use case 2: Specify an output location for the dump

Code:

mongodump --out path/to/directory

Motivation: Sometimes, you may want to save the dump files to a specific directory rather than the default “dump” directory. The --out option allows you to specify the output location for the dump.

Explanation: The --out option is followed by the path to the directory where you want the dump files to be saved. When you provide this option, mongodump will create the specified directory if it doesn’t exist and save the dump files inside it.

Example output: If you run the command mongodump --out /path/to/mybackup, the dump files will be saved in the /path/to/mybackup directory.

/path/to/mybackup/
   database1/
      collection1.bson
      collection2.bson
   database2/
      collection3.bson

Use case 3: Create a dump of a given database

Code:

mongodump --db database_name

Motivation: In some cases, you may only need to create a backup of a specific database rather than all the databases in the MongoDB instance. The --db option allows you to specify the name of the database you want to dump.

Explanation: The --db option is followed by the name of the database you want to create a dump for. When you provide this option, mongodump will only dump the specified database.

Example output: If you run the command mongodump --db mydatabase, it will create a dump of only the “mydatabase” database.

dump/
   mydatabase/
      collection1.bson
      collection2.bson

Use case 4: Create a dump of a given collection within a given database

Code:

mongodump --collection collection_name --db database_name

Motivation: MongoDB collections can have a large number of documents, and in some cases, you may only need a backup of a specific collection within a database. The --collection option allows you to specify the name of the collection you want to dump, along with the name of the database.

Explanation: The --collection option is followed by the name of the collection you want to create a dump for, and the --db option is followed by the name of the database that contains the collection. When you provide these options, mongodump will only dump the specified collection within the specified database.

Example output: If you run the command mongodump --collection mycollection --db mydatabase, it will create a dump of only the “mycollection” collection within the “mydatabase” database.

dump/
   mydatabase/
      mycollection.bson

Use case 5: Connect to a given host running on a given port, and create a dump

Code:

mongodump --host host --port port

Motivation: By default, mongodump connects to the MongoDB instance running on localhost at port 27017. However, in some cases, you may need to connect to a different host and port to create a dump. The --host and --port options allow you to specify the host and port to connect to.

Explanation: The --host and --port options are followed by the hostname or IP address and the port number of the MongoDB instance you want to connect to. When you provide these options, mongodump will connect to the specified host and port to create the dump.

Example output: If you run the command mongodump --host myserver --port 27018, it will connect to the MongoDB instance running on “myserver” at port 27018 and create the dump.

dump/
   database1/
      collection1.bson
      collection2.bson

Use case 6: Create a dump of a given database with a given username; user will be prompted for password

Code:

mongodump --username username --password --db database

Motivation: In MongoDB, databases can be secured with authentication, and you may need to provide a username and password to connect to a database. The --username option allows you to specify the username, and --password prompts you to enter the password for the given username.

Explanation: The --username option is followed by the username you want to use to authenticate with the MongoDB instance. The --password option is used to prompt the user for the password, providing an extra layer of security. Lastly, the --db option is followed by the name of the database you want to create a dump for.

Example output: If you run the command mongodump --username john --password --db mydatabase, it will prompt you to enter the password for the “john” user and create a dump of the “mydatabase” database.

dump/
   mydatabase/
      collection1.bson
      collection2.bson

Use case 7: Create a dump from a specific instance; host, user, password, and database will be defined in the connection string

Code:

mongodump --uri connection_string

Motivation: In some cases, you may have a connection string that includes the hostname, port, username, password, and database information. The --uri option allows you to provide the connection string instead of specifying each individual option separately.

Explanation: The --uri option is followed by the connection string containing all the necessary information to connect to the MongoDB instance, including the hostname, port, username, password, and database. When you provide this option, mongodump will parse the connection string and create the dump accordingly.

Example output: If you run the command mongodump --uri "mongodb://john:password@myserver:27018/mydatabase", it will connect to the MongoDB instance running on “myserver” at port 27018 using the “john” user with the given password, and create a dump of the “mydatabase” database.

dump/
   mydatabase/
      collection1.bson
      collection2.bson

Conclusion:

The mongodump command is a powerful utility for creating backups of MongoDB databases and collections. It provides a variety of options to customize the backup process, allowing you to create dumps of all databases, specific databases or collections, and connect to different hosts and ports. Whether you need to migrate data, recover from data loss, or simply create regular backups, the mongodump command is an essential tool for managing your MongoDB instances.