dbStats (original) (raw)

dbStats

The dbStats command returns storage statistics for a given database.

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 has limited support in M0, M2, M5, and Flex 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

The command has the following syntax:


db.runCommand(

   {

     dbStats: 1,

     scale: <number>,

     freeStorage: 0

   }

)

The command takes the following fields:

Fields	Description
dbStats	1
scale	Optional. The scale factor for the various size data. Thescale defaults to 1 to return size data in bytes. To display kilobytes rather than bytes, specify a scalevalue of 1024.If you specify a non-integer scale factor, MongoDB uses the integer part of the specified factor. For example, if you specify a scale factor of 1023.999, MongoDB uses 1023as the scale factor.Starting in version 4.2, the output includes the scaleFactorused to scale the size values.
freeStorage	Optional. To return details on free space allocated to collections, set freeStorage to 1.If the instance has a large number of collections or indexes, obtaining free space usage data may cause processing delays. To gather dbStats information without free space details, either set freeStorage to 0 or do not include the field.

In mongosh, the db.stats() function provides a wrapper around dbStats.

The time required to run the command depends on the total size of the database. Because the command must touch all data files, the command may take several seconds to run.

After an unclean shutdown of a mongod using the Wired Tiger storage engine, count and size statistics reported bydbStats may be inaccurate.

The amount of drift depends on the number of insert, update, or delete operations performed between the last checkpoint and the unclean shutdown. Checkpoints usually occur every 60 seconds. However, mongod instances running with non-default --syncdelay settings may have more or less frequent checkpoints.

Run validate on each collection on the mongodto restore statistics after an unclean shutdown.

After an unclean shutdown:

validate updates the count statistic in the collStats output with the latest value.
Other statistics like the number of documents inserted or removed in the collStats output are estimates.

To run on a replica set member, dbStats operations require the member to be in PRIMARY or SECONDARY state. If the member is in another state, such as STARTUP2, the operation errors.

dbStats.db

Name of the database.

dbStats.collections

Number of collections in the database.

dbStats.views

Number of views in the database.

dbStats.objects

Number of objects (specifically, documents) in the database across all collections.

dbStats.avgObjSize

Average size of each document in bytes. This is thedataSize divided by the number of documents. Thescale argument does not affect theavgObjSize value.

dbStats.dataSize

Total size of the uncompressed data held in the database. ThedataSize decreases when you remove documents.

For databases using the WiredTiger storage engine, dataSize may be larger than storageSize if compression is enabled. ThedataSize decreases when documents shrink.

dbStats.storageSize

Sum of the disk space allocated to all collections in the database fordocument storage, including free space.

The storageSize does not decrease as you remove or shrink documents. This value may be smaller thandataSize for databases using the WiredTiger storage engine with compressionenabled.

storageSize does not include space allocated to indexes. See indexSize for the total index size.

dbStats.freeStorageSize

Sum of the free space allocated to all collections in the database for document storage. Free database storage space is allocated to the collection but does not contain data.

freeStorageSize does not include free space allocated to indexes. See indexFreeStorageSize for the total free index size.

To include this value in the dbStats output, setfreeStorage to 1.

Updated in version 5.3.0, 5.2.1, and 5.0.6

dbStats.indexes

Total number of indexes across all collections in the database.

dbStats.indexSize

Sum of the disk space allocated to all indexes in the database, including free index space.

dbStats.indexFreeStorageSize

Sum of the free disk space allocated to all indexes in the database. Free database storage space is allocated to the index but does not contain data.

indexFreeStorageSize does not include free space allocated to document storage. See freeStorageSizefor the total free document storage size.

indexFreeStorageSize does not include in-progress index builds.

To include this value in the dbStats output, setfreeStorage to 1.

Updated in version 7.0, 6.3.2, 6.0.7, 5.3.0, 5.2.1, 5.0.19, and 5.0.6

dbStats.totalSize

Sum of the disk space allocated for both documents and indexes in all collections in the database. Includes used and free storage space. This is the sum of storageSize andindexSize.

dbStats.totalFreeStorageSize

Sum of the free storage space allocated for both documents and indexes in all collections in the database. This is the sum offreeStorageSize andindexFreeStorageSize.

To include this value in the dbStats output, setfreeStorage to 1.

Updated in version 5.3.0, 5.2.1, and 5.0.6.

dbStats.scaleFactor

scale value used by the command.

If you specified a non-integer scale factor, MongoDB uses the integer part of the specified factor. For example, if you specify a scale factor of 1023.999, MongoDB uses 1023 as the scale factor.

dbStats.fsUsedSize

Total size of all disk space in use on the filesystem where MongoDB stores data.