$sortByCount

Groups documents by the supplied expression, counts each group, and sorts the results by count in descending order.

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Syntax

{ "$sortByCount": <expression> }

• The expression can be a field path ("$status"), system variable, or computed expression.
• The output documents contain _id (group key) and count.

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Example

Input

[
  { "status": "OPEN" },
  { "status": "OPEN" },
  { "status": "CLOSED" },
  { "status": "FAILED" },
  { "status": "OPEN" }
]

Stage

{ "$sortByCount": "$status" }

Output

[
  { "_id": "OPEN", "count": 3 },
  { "_id": "CLOSED", "count": 1 },
  { "_id": "FAILED", "count": 1 }
]

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Tips

• When you already have grouped data, consider $group + $sort for more control over additional fields.
• Combine with $match beforehand to limit the documents being counted.