cloneCollection¶

On this page

Definition
Behavior
Example

Definition¶

cloneCollection¶

Deprecated since version 4.2: MongoDB deprecates cloneCollection and its helper db.cloneCollection(). For alternatives, see Deprecate Support for cloneCollection.

Copies a collection from a remote mongod instance to the current mongod instance. cloneCollection creates a collection in a database with the same name as the remote collection’s database. cloneCollection takes the following form:

copy

{ cloneCollection: "<namespace>",
  from: "<hostname>",
  query: { <query> },
  writeConcern: { <write concern> }
}

cloneCollection has the following fields:

Field	Type	Description
`cloneCollection`	string	The namespace of the collection to copy. The namespace is a combination of the database name and the name of the collection.
`from`	string	The address of the server to clone from.
`query`	document	Optional. A query that filters the documents in the source collection that `cloneCollection` will copy to the current database.
`writeConcern`	document	Optional. A document that expresses the write concern for the operation. Omit to use the default write concern.

The mongo shell provides the method db.cloneCollection() as a wrapper for the cloneCollection command.

Behavior¶

`mongos`¶

mongos does not support cloneCollection.

Authorization¶

cloneCollection cannot be used if the from server has authorization enabled.

Namespace¶

If the given namespace already exists in the destination mongod instance, cloneCollection will return an error.

FeatureCompatibilityVersion¶

You cannot copy data between a MongoDB 4.0 mongod instance with featureCompatibilityVersion (FCV) 4.0 and a MongoDB version 3.6 mongod instance.

Note

You cannot copy data between a MongoDB 4.0 mongod instance (regardless of the FCV value) and a MongoDB 3.4 and earlier mongod instance.

For example:

Instance 1	Instance 2
Version 4.0 `mongod` with FCV 4.0	Version 4.0 `mongod` with FCV 4.0	Can copy data.
Version 4.0 `mongod` with FCV 4.0	Version 4.0 `mongod` with FCV 3.6	Can copy data.
Version 4.0 `mongod` with FCV 4.0	Version 3.6 `mongod` with FCV 3.6	Cannot copy data. Instance 2 must be a MongoDB version 4.0
Version 4.0 `mongod` with FCV 3.6	Version 3.6 `mongod` with FCV 3.6	Can copy data.
Version 4.0 `mongod` with FCV 3.6	Version 3.6 `mongod` with FCV 3.4	Can copy data.

In general, if the mongod instance has its featureCompatibilityVersion (FCV) set to its MongoDB version, you cannot copy data between that instance and a mongod instance of an earlier MongoDB version.

Operations that copy data include:

db.cloneCollection() and the command cloneCollection
db.cloneDatabase() and the command clone
db.copyDatabase() and the command copydb

Example¶