Copy Database Commands

MongoDB includes commands for copying a database from one server to another.

These options are faster than the alternative of doing a mongodump and mongorestore since they skip the step of creating a temporary on-disk BSON representation.

copydb Command

Copies an entire database from one name on one server to another name on another server. omit <from_hostname> to copy from one name to another on the same server. Cann must be sent/run on the "destination" server.

> // shell helper syntax:
> db.copyDatabase(<from_dbname>, <to_dbname>, <from_hostname>);

> // if you must authenticate with the source database
> db.copyDatabase(<from_dbname>, <to_dbname>, <from_hostname>, <username>, <password>);

> // pure command syntax (runnable from any driver):
> db.runCommand(
... {copydb: 1, fromhost: <hostname>, fromdb: <db>,
...  todb: <db>[, slaveOk: <bool>, username: <username>,
...  nonce: <nonce>, key: <key>]}";

> // command syntax for authenticating with the source:
> n = db.runCommand( { copydbgetnonce : 1, fromhost: ... } );
db.runCommand( { copydb : 1, fromhost: ..., fromdb: ..., todb: ..., username: ..., nonce: n.nonce, key: <hash of username, nonce, password > } );

cloneDatabase

Similar to copydb but with a simplified syntax for the case where we simply want to copy a database to this server, and leave its name as-is.

> db.cloneDatabase(<from_hostname>);

The copy database command does not work when copying to or from a sharded collection.

Other Notes

copyDatabase may be run against a slave/secondary (i.e., the source server can be a slave/secondary).
copyDatabase does not snapshot in any sense: if the source database is changing during the copy, the destination will receive documents representing different points in time in the source during the copying interval.
The command must be run on the destination server.
The command does not lock either the source or the destination server for the duration of the operation. Each side will yield periodically to allow other reads/writes through.

Copy Database Commands

copydb Command

cloneDatabase

Other Notes

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