dataSize

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Definition

Compatibility
Syntax
Command Fields
Example

MongoDB 5.0 is end of life as of October 2024. This version of the documentation is no longer supported. To upgrade your 5.0 deployment, see the MongoDB 6.0 upgrade procedures.

Definition

dataSize: The dataSize command returns the size in bytes for the specified data.

Compatibility

This command is available in deployments hosted in the following environments:

MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Important

This command is not supported in M0, M2, and M5 clusters. For more information, see Unsupported Commands.

MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The command has the following syntax:

{
    dataSize: <string>,
    keyPattern: <document>,
    min: <document>,
    max: <document>,
    estimate: <boolean>
}

Command Fields

The command takes the following fields:

Field	Type	Description
`dataSize`	string	The name of the target collection.
`keyPattern`	document	Optional. The collection's key pattern to examine. The collection must have an index with the corresponding pattern. Otherwise `dataSize` returns an error message.
`min`	document	Optional. The lower bound of the key range to be examined.
`max`	document	Optional. The upper bound of the key range to be examined.
`estimate`	boolean	Optional. When `true`, `dataSize` estimates the data size by assuming that all documents in the specified range are uniformly sized as per the collection's average object size. The collection's average object size is obtained from the `avgObjSize` field in the output of the `collStats` command. Defaults to false.

Example

The following operation runs the dataSize command on the database.collection collection, specifying a key pattern of {field: 1} with the lower bound of the range of keys to be examined being {field: 10} and the upper bound of the key to be examined being {field: 100}.

db.runCommand({ dataSize: "database.collection", keyPattern: { field: 1 }, min: { field: 10 }, max: { field: 100 } })

This returns a document with the size in bytes for all matching documents. Replace database.collection with the database and collection from your deployment.

The amount of time required to return dataSize depends on the amount of data in the collection.

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