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db.collection.getShardDistribution()

On this page

  • Definition
  • Syntax
  • Output

Definition

db.collection.getShardDistribution()

Important

mongosh Method

This page documents a mongosh method. This is not the documentation for a language-specific driver, such as Node.js.

For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.

Prints the data distribution statistics for a sharded collection.

Syntax

The getShardDistribution() method has the following form:

db.collection.getShardDistribution()

Tip

See also:

Sharding

Output

Sample Output

The following is a sample output for the distribution of a sharded collection:

Shard shard01 at shard01/localhost:27018
{
  data: '38.14MB',
  docs: 1000003,
  chunks: 2,
  'estimated data per chunk': '19.07B',
  'estimated docs per chunk': 500001
}
---
Shard shard02 at shard02/localhost:27019
{
  data: '38.14B',
  docs: 999999,
  chunks: 3,
  'estimated data per chunk': '12.71B',
  'estimated docs per chunk': 333333
}
---
Totals
{
  data: '76.29B',
  docs: 2000002,
  chunks: 5,
  'Shard shard01': [ '50 % data', '50 % docs in cluster', '40B avg obj size on shard' ],
  'Shard shard02': [ '49.99 % data', '49.99 % docs in cluster', '40B avg obj size on shard' ]
}

Output Fields

Shard shard01 at <host-a>   {
  data: <size-a>,
  docs: <count-a>,
  chunks: <number of chunks-a>,
  'estimated data per chunk': <size-a>/<number of chunks-a>,
  'estimated docs per chunk': <count-a>/<number of chunks-a>
}
---
Shard shard02 at <host-b>
{
  data: <size-b>,
  docs: <count-b>,
  chunks: <number of chunks-b>,
  'estimated data per chunk': <size-b>/<number of chunks-b>,
  'estimated docs per chunk': <count-b>/<number of chunks-b>
}
---
Totals
{
  data: <stats.size>,
  docs: <stats.count>,
  chunks: <calc total chunks>,
  Shard shard01: [ <estDataPercent-a> % data, <estDocPercent-a> % docs in cluster, stats.shards[ <shard-a> ].avgObjSize avg obj size on shard ],
  Shard shard02: [ <estDataPercent-b> % data, <estDocPercent-b> % docs in cluster, stats.shards[ <shard-b> ].avgObjSize avg obj size on shard ]
}

The output information displays:

  • <shard-x> is a string that holds the shard name.

  • <host-x> is a string that holds the host name(s).

  • <size-x> is a number that includes the size of the data, including the unit of measure (e.g. b, Mb).

  • <count-x> is a number that reports the number of documents in the shard.

  • <number of chunks-x> is a number that reports the number of chunks in the shard.

  • <size-x>/<number of chunks-x> is a calculated value that reflects the estimated data size per chunk for the shard, including the unit of measure (e.g. b, Mb).

  • <count-x>/<number of chunks-x> is a calculated value that reflects the estimated number of documents per chunk for the shard.

  • <stats.size> is a value that reports the total size of the data in the sharded collection, including the unit of measure.

  • <stats.count> is a value that reports the total number of documents in the sharded collection.

  • <calc total chunks> is a calculated number that reports the number of chunks from all shards, for example:

    <calc total chunks> = <number of chunks-a> + <number of chunks-b>

  • <estDataPercent-x> is a calculated value that reflects, for each shard, the data size as the percentage of the collection's total data size, for example:

    <estDataPercent-x> = <size-x>/<stats.size>

  • <estDocPercent-x> is a calculated value that reflects, for each shard, the number of documents as the percentage of the total number of documents for the collection, for example:

    <estDocPercent-x> = <count-x>/<stats.count>

  • stats.shards[ <shard-x> ].avgObjSize is a number that reflects the average object size, including the unit of measure, for the shard.

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