$bitOr (bitwise expression)

APPLIES TO: MongoDB vCore

The $bitOr operator performs a bitwise OR operation on integer values. It compares each bit of the first operand to the corresponding bit of the second operand. If either bit is 1, the corresponding result bit is set to 1. If both bits are 0, the corresponding result bit is set to 0.

The syntax for the $bitOr operator is as follows:

{
  $bitOr: [ <expression1>, <expression2>, ... ]
}

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

{
  "_id": "f2a8c190-28e4-4e14-9d8b-0256e53dca66",
  "name": "Fabrikam, Inc. | Car Accessory Outlet - West Adele",
  "location": {
    "lat": -47.2548,
    "lon": -38.4071
  },
  "staff": {
    "totalStaff": {
      "fullTime": 3,
      "partTime": 2
    }
  },
  "sales": {
    "totalSales": 31211,
    "salesByCategory": [
      {
        "categoryName": "Phone Mounts",
        "totalSales": 8911
      },
      {
        "categoryName": "Dash Cameras",
        "totalSales": 22300
      }
    ]
  },
  "promotionEvents": [
    {
      "eventName": "Super Saver Spectacular",
      "promotionalDates": {
        "startDate": {
          "Year": 2024,
          "Month": 3,
          "Day": 25
        },
        "endDate": {
          "Year": 2024,
          "Month": 4,
          "Day": 1
        }
      },
      "discounts": [
        {
          "categoryName": "Car Chargers",
          "discountPercentage": 7
        },
        {
          "categoryName": "Dash Cameras",
          "discountPercentage": 11
        }
      ]
    }
  ]
}

Perform a bitwise OR operation on staff numbers to combine permission flags.

db.stores.aggregate([
  { $match: {"_id": "f2a8c190-28e4-4e14-9d8b-0256e53dca66"} },
  {
    $project: {
      name: 1,
      fullTimeStaff: "$staff.totalStaff.fullTime",
      partTimeStaff: "$staff.totalStaff.partTime",
      combinedStaffFlag: {
        $bitOr: ["$staff.totalStaff.fullTime", "$staff.totalStaff.partTime"]
      }
    }
  }
])

This will produce the following output:

[
  {
    _id: 'f2a8c190-28e4-4e14-9d8b-0256e53dca66',
    name: 'Fabrikam, Inc. | Car Accessory Outlet - West Adele',
    fullTimeStaff: 3,
    partTimeStaff: 2,
    combinedStaffFlag: 3
  }
]

The bitwise OR of 3 (011 in binary) and 2 (010 in binary) equals 3 (011 in binary).

Apply bitwise OR operations on sales figures to create combined flags.

db.stores.aggregate([
  { $match: {"_id": "f2a8c190-28e4-4e14-9d8b-0256e53dca66"} },
  { $unwind: "$sales.salesByCategory" },
  {
    $project: {
      name: 1,
      categoryName: "$sales.salesByCategory.categoryName",
      totalSales: "$sales.salesByCategory.totalSales",
      // Combine lower 8 bits of sales with a base flag (15 = 00001111)
      salesFlag: {
        $bitOr: [
          { $toInt: { $mod: ["$sales.salesByCategory.totalSales", 256] } },
          15
        ]
      }
    }
  }
])

This will produce the following output:

[
  {
    _id: 'f2a8c190-28e4-4e14-9d8b-0256e53dca66',
    name: 'Fabrikam, Inc. | Car Accessory Outlet - West Adele',
    categoryName: 'Phone Mounts',
    totalSales: 8911,
    salesFlag: 207
  },
  {
    _id: 'f2a8c190-28e4-4e14-9d8b-0256e53dca66',
    name: 'Fabrikam, Inc. | Car Accessory Outlet - West Adele',
    categoryName: 'Dash Cameras',
    totalSales: 22300,
    salesFlag: 31
  }
]

Perform bitwise OR operation on multiple discount values.

db.stores.aggregate([
  { $match: {"_id": "f2a8c190-28e4-4e14-9d8b-0256e53dca66"} },
  { $unwind: "$promotionEvents" },
  { $match: {"promotionEvents.eventName": "Super Saver Spectacular"} },
  {
    $project: {
      name: 1,
      eventName: "$promotionEvents.eventName",
      discountFlags: {
        $map: {
          input: "$promotionEvents.discounts",
          as: "discount",
          in: {
            categoryName: "$$discount.categoryName",
            discountPercentage: "$$discount.discountPercentage",
            combinedFlag: {
              $bitOr: [
                "$$discount.discountPercentage",
                "$staff.totalStaff.fullTime",
                "$staff.totalStaff.partTime"
              ]
            }
          }
        }
      }
    }
  }
])

This will produce the following output:

[
  {
    _id: 'f2a8c190-28e4-4e14-9d8b-0256e53dca66',
    name: 'Fabrikam, Inc. | Car Accessory Outlet - West Adele',
    eventName: 'Super Saver Spectacular',
    discountFlags: [
      {
        categoryName: 'Car Chargers',
        discountPercentage: 7,
        combinedFlag: 7
      },
      {
        categoryName: 'Dash Cameras',
        discountPercentage: 11,
        combinedFlag: 11
      }
    ]
  }
]

The operation combines discount percentages with staff numbers using bitwise OR: 7|3|2 = 7 and 11|3|2 = 11.

Use bitwise OR to create permission flags by combining different access levels.

db.stores.aggregate([
  { $match: {"_id": "f2a8c190-28e4-4e14-9d8b-0256e53dca66"} },
  {
    $project: {
      name: 1,
      // Create permission flags: 1=read, 2=write, 4=execute
      readPermission: 1,
      writePermission: 2,
      executePermission: 4,
      fullPermissions: {
        $bitOr: [1, 2, 4]
      },
      staffBasedPermissions: {
        $bitOr: [
          "$staff.totalStaff.fullTime",
          "$staff.totalStaff.partTime",
          8
        ]
      }
    }
  }
])

This will produce the following output:

[
  {
    _id: 'f2a8c190-28e4-4e14-9d8b-0256e53dca66',
    name: 'Fabrikam, Inc. | Car Accessory Outlet - West Adele',
    fullPermissions: 7,
    staffBasedPermissions: 11
  }
]

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