$mod
The $mod operator performs a modulo operation on the value of a field and selects documents with a specified result.
$mod
The $mod operator performs a modulo operation on the value of a field and selects documents with a specified result. This operator is useful for finding documents where a numeric field value, when divided by a divisor, leaves a specific remainder. It commonly serves for pagination, sampling data, or finding patterns in numeric sequences.
Parameters
| Parameter | Description |
|---|---|
<field> | The field to perform the modulo operation on. The field must contain numeric values. |
<divisor> | The number to divide the field value by. Must be a positive number. |
<remainder> | The expected remainder after the modulo operation. Must be a non-negative number less than the divisor. |
Examples
Consider this sample document from the stores collection.
{
"_id": "0fcc0bf0-ed18-4ab8-b558-9848e18058f4",
"name": "First Up Consultants | Beverage Shop - Satterfieldmouth",
"location": {
"lat": -89.2384,
"lon": -46.4012
},
"staff": {
"totalStaff": {
"fullTime": 8,
"partTime": 20
}
},
"sales": {
"totalSales": 75670,
"salesByCategory": [
{
"categoryName": "Wine Accessories",
"totalSales": 34440
},
{
"categoryName": "Bitters",
"totalSales": 39496
},
{
"categoryName": "Rum",
"totalSales": 1734
}
]
},
"promotionEvents": [
{
"eventName": "Unbeatable Bargain Bash",
"promotionalDates": {
"startDate": {
"Year": 2024,
"Month": 6,
"Day": 23
},
"endDate": {
"Year": 2024,
"Month": 7,
"Day": 2
}
},
"discounts": [
{
"categoryName": "Whiskey",
"discountPercentage": 7
},
{
"categoryName": "Bitters",
"discountPercentage": 15
},
{
"categoryName": "Brandy",
"discountPercentage": 8
},
{
"categoryName": "Sports Drinks",
"discountPercentage": 22
},
{
"categoryName": "Vodka",
"discountPercentage": 19
}
]
},
{
"eventName": "Steal of a Deal Days",
"promotionalDates": {
"startDate": {
"Year": 2024,
"Month": 9,
"Day": 21
},
"endDate": {
"Year": 2024,
"Month": 9,
"Day": 29
}
},
"discounts": [
{
"categoryName": "Organic Wine",
"discountPercentage": 19
},
{
"categoryName": "White Wine",
"discountPercentage": 20
},
{
"categoryName": "Sparkling Wine",
"discountPercentage": 19
},
{
"categoryName": "Whiskey",
"discountPercentage": 17
},
{
"categoryName": "Vodka",
"discountPercentage": 23
}
]
}
]
}Example 1: Find stores with sales divisible by 1000
This query retrieves stores where the total sales are divisible by 1000 (useful for identifying round sales figures).
db.stores.find({
"sales.totalSales": { $mod: [1000, 0] }
}).limit(2)The first two results returned by this query are:
[
{
"_id": "new-store-001",
"name": "TechWorld Electronics - Downtown Branch",
"sales": {
"totalSales": 5000
},
"createdDate": "2025-06-11T11:11:32.262Z",
"status": "new",
"staff": {
"totalStaff": {
"fullTime": 0,
"partTime": 0
}
},
"version": 1
},
{
"_id": "gaming-store-mall-001",
"name": "Gaming Paradise - Mall Location",
"location": {
"lat": 35.6762,
"lon": 139.6503
},
"createdDate": "2025-06-11T11:13:27.180Z",
"status": "active",
"staff": {
"totalStaff": {
"fullTime": 8,
"partTime": 12
},
"manager": "Alex Johnson",
"departments": [
"gaming",
"accessories",
"repairs"
]
},
"sales": {
"totalSales": 0,
"salesByCategory": []
},
"operatingHours": {
"weekdays": "10:00-22:00",
"weekends": "09:00-23:00"
},
"metadata": {
"version": 1,
"source": "store-management-system"
}
}
]Example 2: Pagination-style querying
This query retrieves stores where the part-time employee count leaves a remainder of 0 when divided by 4 (useful for creating data subsets).
db.stores.find({
"staff.totalStaff.partTime": { $mod: [4, 0] }
})The first two results returned by this query are:
[
{
"_id": "new-store-001",
"name": "TechWorld Electronics - Downtown Branch",
"sales": {
"totalSales": 5000
},
"createdDate": "2025-06-11T11:11:32.262Z",
"status": "new",
"staff": {
"totalStaff": {
"fullTime": 0,
"partTime": 0
}
},
"version": 1
},
{
"_id": "gaming-store-mall-001",
"name": "Gaming Paradise - Mall Location",
"location": {
"lat": 35.6762,
"lon": 139.6503
},
"createdDate": "2025-06-11T11:13:27.180Z",
"status": "active",
"staff": {
"totalStaff": {
"fullTime": 8,
"partTime": 12
},
"manager": "Alex Johnson",
"departments": [
"gaming",
"accessories",
"repairs"
]
},
"sales": {
"totalSales": 0,
"salesByCategory": []
},
"operatingHours": {
"weekdays": "10:00-22:00",
"weekends": "09:00-23:00"
},
"metadata": {
"version": 1,
"source": "store-management-system"
}
}
]