$millisecond (date expression)

APPLIES TO: MongoDB vCore

The $millisecond operator extracts the milliseconds portion from a date value, returning a number between 0 and 999. This operator is useful for precise timestamp analysis and filtering operations that require millisecond-level granularity.

Syntax

The syntax for the $millisecond operator is as follows:

{
  $millisecond: <dateExpression>
}

Parameters

Description
dateExpression An expression that resolves to a Date, a Timestamp, or an ObjectId. If the expression resolves to null or is missing, $millisecond returns null.

Example

Let's understand the usage with sample JSON from the stores dataset.

{
  "_id": "905d1939-e03a-413e-a9c4-221f74055aac",
  "name": "Trey Research | Home Office Depot - Lake Freeda",
  "location": { "lat": -48.9752, "lon": -141.6816 },
  "staff": { "employeeCount": { "fullTime": 12, "partTime": 19 } },
  "sales": {
    "salesByCategory": [ { "categoryName": "Desk Lamps", "totalSales": 37978 } ],
    "revenue": 37978
  },
  "company": "Trey Research",
  "city": "Lake Freeda",
  "storeOpeningDate": ISODate("2024-09-26T22:55:25.779Z"),
  "lastUpdated": Timestamp({ "t": 1729983325, "i": 1 })
}

Example 1: Extract milliseconds from store opening date

This example extracts the milliseconds portion from the store opening date.

db.stores.aggregate([
  { $match: {"_id": "905d1939-e03a-413e-a9c4-221f74055aac"} },
  {
    $project: {
      name: 1,
      storeOpeningDate: 1,
      openingMilliseconds: {
        $millisecond: "$storeOpeningDate"
      }
    }
  }
])

The query returns the milliseconds portion (779) from the store opening timestamp.

{
  "_id": "905d1939-e03a-413e-a9c4-221f74055aac",
  "name": "Trey Research | Home Office Depot - Lake Freeda",
  "storeOpeningDate": ISODate("2024-09-26T22:55:25.779Z"),
  "openingMilliseconds": 779
}

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