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db.collection.dataSize()Important
mongo Shell Method
This page documents a
mongomethod. This is not the documentation for database commands or language-specific drivers, such as Node.js. To use the database command, see thesizefield returned by thecollStatscommand.For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.
Returns: The size in bytes of the collection. Data compressiondoes not affect this value.Starting in MongoDB 4.4, to run on a replica set member,
collStatsoperations require the member to be inPRIMARYorSECONDARYstate. If the member is in another state, such asSTARTUP2, the operation errors.In previous versions, the operations also run when the member is in
STARTUP2. The operations wait until the member transitioned toRECOVERING.