$denseRank
The $denseRank operator assigns and returns a positional ranking for each document within a partition based on a specified sort order
$denseRank
The $denseRank operator sorts documents on one or more fields within a partition and assigns a ranking for each document relative to other documents in the result set.
Examples
Consider this sample document from the stores collection.
{
"_id": "0fcc0bf0-ed18-4ab8-b558-9848e18058f4",
"name": "First Up Consultants | Beverage Shop - Satterfieldmouth",
"location": {
"lat": -89.2384,
"lon": -46.4012
},
"staff": {
"totalStaff": {
"fullTime": 8,
"partTime": 20
}
},
"sales": {
"totalSales": 75670,
"salesByCategory": [
{
"categoryName": "Wine Accessories",
"totalSales": 34440
},
{
"categoryName": "Bitters",
"totalSales": 39496
},
{
"categoryName": "Rum",
"totalSales": 1734
}
]
},
"promotionEvents": [
{
"eventName": "Unbeatable Bargain Bash",
"promotionalDates": {
"startDate": {
"Year": 2024,
"Month": 6,
"Day": 23
},
"endDate": {
"Year": 2024,
"Month": 7,
"Day": 2
}
},
"discounts": [
{
"categoryName": "Whiskey",
"discountPercentage": 7
},
{
"categoryName": "Bitters",
"discountPercentage": 15
},
{
"categoryName": "Brandy",
"discountPercentage": 8
},
{
"categoryName": "Sports Drinks",
"discountPercentage": 22
},
{
"categoryName": "Vodka",
"discountPercentage": 19
}
]
},
{
"eventName": "Steal of a Deal Days",
"promotionalDates": {
"startDate": {
"Year": 2024,
"Month": 9,
"Day": 21
},
"endDate": {
"Year": 2024,
"Month": 9,
"Day": 29
}
},
"discounts": [
{
"categoryName": "Organic Wine",
"discountPercentage": 19
},
{
"categoryName": "White Wine",
"discountPercentage": 20
},
{
"categoryName": "Sparkling Wine",
"discountPercentage": 19
},
{
"categoryName": "Whiskey",
"discountPercentage": 17
},
{
"categoryName": "Vodka",
"discountPercentage": 23
}
]
}
]
}Example 1 - Retrieve a document rank for each store
To calculate a document rank for each store under the First Up Consultants company, first run a query to filter on the company, then sort the resulting documents in descending order of sales and assign a document rank to each document in the sorted result set.
db.stores.aggregate([{
"$match": {
"company": {
"$in": ["First Up Consultants"]
}
}
}, {
"$setWindowFields": {
"partitionBy": "$company",
"sortBy": {
"sales.totalSales": -1
},
"output": {
"denseRank": {
"$denseRank": {}
}
}
}
}, {
"$project": {
"company": 1,
"sales.totalSales": 1,
"denseRank": 1
}
}])The first five results returned by this query are:
[
{
"_id": "a0386810-b6f8-4b05-9d60-e536fb2b0026",
"sales": {
"revenue": 327583
},
"company": "First Up Consultants",
"denseRank": 1
},
{
"_id": "ad8af64a-d5bb-4162-9bb6-e5104126566d",
"sales": {
"revenue": 288582
},
"company": "First Up Consultants",
"denseRank": 2
},
{
"_id": "39acb3aa-f350-41cb-9279-9e34c004415a",
"sales": {
"revenue": 279183
},
"company": "First Up Consultants",
"denseRank": 3
},
{
"_id": "cd3d3782-17d1-451e-8b0f-4f10a68a8db7",
"sales": {
"revenue": 271604
},
"company": "First Up Consultants",
"denseRank": 4
},
{
"_id": "63ac4722-fc87-4526-a5e0-b5767d2807f7",
"sales": {
"revenue": 260409
},
"company": "First Up Consultants",
"denseRank": 5
}
]