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mongodump

Synopsis

mongodump is a utility for creating a binary export of the contents of a database. Consider using this utility as part an effective backup strategy. Use mongodump in conjunction with mongorestore to restore databases.

mongodump can read data from either mongod or mongos instances, in addition to reading directly from MongoDB data files without an active mongod.

Note

Data created by the mongodump tool from the 2.2 distribution is incompatible with versions of mongorestore from the 2.0 distribution and earlier.

Options

mongodump
--help

Returns a basic help and usage text.

--verbose, -v

Increases the amount of internal reporting returned on the command line. Increase the verbosity with the -v form by including the option multiple times, (e.g. -vvvvv.)

--version

Returns the version of the mongodump utility and exits.

--host <hostname><:port>

Specifies a resolvable hostname for the mongod that you wish to use to create the database dump. By default mongodump will attempt to connect to a MongoDB process ruining on the localhost port number 27017.

Optionally, specify a port number to connect a MongoDB instance running on a port other than 27017.

To connect to a replica set, use the --host argument with a setname, followed by a slash and a comma-separated list of host names and port numbers. The mongodump utility will, given the seed of at least one connected set member, connect to the primary member of that set. This option would resemble:

mongodump --host repl0/mongo0.example.net,mongo0.example.net:27018,mongo1.example.net,mongo2.example.net

You can always connect directly to a single MongoDB instance by specifying the host and port number directly.

--port <port>

Specifies the port number, if the MongoDB instance is not running on the standard port. (i.e. 27017) You may also specify a port number using the --host option.

--ipv6

Enables IPv6 support that allows mongodump to connect to the MongoDB instance using an IPv6 network. All MongoDB programs and processes, including mongodump, disable IPv6 support by default.

--username <username>, -u <username>

Specifies a username to authenticate to the MongoDB instance, if your database requires authentication. Use in conjunction with the --password option to supply a password.

--password <password>

Specifies a password to authenticate to the MongoDB instance. Use in conjunction with the --username option to supply a username.

If you specify a --username without the --password option, mongodump will prompt for a password interactively.

--dbpath <path>

Specifies the directory of the MongoDB data files. If used, the --dbpath option enables mongodump to attach directly to local data files and copy the data without the mongod. To run with --dbpath, mongodump needs to restrict access to the data directory: as a result, no mongod can access the same path while the process runs.

--directoryperdb

Use the --directoryperdb in conjunction with the corresponding option to mongod. This option allows mongodump to read data files organized with each database located in a distinct directory. This option is only relevant when specifying the --dbpath option.

--journal

Allows mongodump operations to use the durability journal to ensure that the export is in a consistent state. This option is only relevant when specifying the --dbpath option.

--db <db>, -d <db>

Use the --db option to specify a database for mongodump to backup. If you do not specify a DB, mongodump copies all databases in this instance into the dump files. Use this option to backup or copy a smaller subset of your data.

--collection <collection>, -c <collection>

Use the --collection option to specify a collection for mongodump to backup. If you do not specify a collection, this option copies all collections in the specified database or instance to the dump files. Use this option to backup or copy a smaller subset of your data.

--out <path>, -o <path>

Specifies a directory where mongodump saves the output of the database dump. By default, mongodump saves output files in a directory named dump in the current working directory.

To send the database dump to standard output, specify “-” instead of a path. Write to standard output if you want process the output before saving it, such as to use gzip to compress the dump. When writing standard output, mongodump does not write the metadata that writes in a <dbname>.metadata.json file when writing to files directly.

--query <json>, -q <json>

Provides a query to limit (optionally) the documents included in the output of mongodump.

--oplog

Use this option to ensure that mongodump creates a dump of the database that includes an oplog, to create a point-in-time snapshot of the state of a mongod instance. To restore to a specific point-in-time backup, use the output created with this option in conjunction with mongorestore --oplogReplay.

Without --oplog, if there are write operations during the dump operation, the dump will not reflect a single moment in time. Changes made to the database during the update process can affect the output of the backup.

--oplog has no effect when running mongodump against a mongos instance to dump the entire contents of a sharded cluster. However, you can use --oplog to dump individual shards.

Note

--oplog only works against nodes that maintain an oplog. This includes all members of a replica set, as well as master nodes in master/slave replication deployments.

--repair

Use this option to run a repair option in addition to dumping the database. The repair option attempts to repair a database that may be in an inconsistent state as a result of an improper shutdown or mongod crash.

--forceTableScan

Forces mongodump to scan the data store directly: typically, mongodump saves entries as they appear in the index of the _id field. Use --forceTableScan to skip the index and scan the data directly. Typically there are two cases where this behavior is preferable to the default:

  1. If you have key sizes over 800 bytes that would not be present in the _id index.
  2. Your database uses a custom _id field.

When you run with --forceTableScan, mongodump does not use $snapshot. As a result, the dump produced by mongodump can reflect the state of the database at many different points in time.

Warning

Use --forceTableScan with extreme caution and consideration.

Warning

Changed in version 2.2: When used in combination with fsync or db.fsyncLock(), mongod may block some reads, including those from mongodump, when queued write operation waits behind the fsync lock.

Behavior

When running mongodump against a mongos instance where the sharded cluster consists of replica sets, the read preference of the operation will prefer reads from secondary members of the set.

Usage

See the Use mongodump and mongorestore to Backup and Restore MongoDB Databases for a larger overview of mongodump usage. Also see the “mongorestore” document for an overview of the mongorestore, which provides the related inverse functionality.

The following command, creates a dump file that contains only the collection named collection in the database named test. In this case the database is running on the local interface on port 27017:

mongodump --collection collection --db test

In the next example, mongodump creates a backup of the database instance stored in the /srv/mongodb directory on the local machine. This requires that no mongod instance is using the /srv/mongodb directory.

mongodump --dbpath /srv/mongodb

In the final example, mongodump creates a database dump located at /opt/backup/mongodump-2011-10-24, from a database running on port 37017 on the host mongodb1.example.net and authenticating using the username user and the password pass, as follows:

mongodump --host mongodb1.example.net --port 37017 --username user --password pass /opt/backup/mongodump-2011-10-24
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