$indexStats
The $indexStats stage returns usage statistics for each index in the collection.
$indexStats
The $indexStats aggregation stage returns usage statistics for each index in the collection. This stage is useful for analyzing index performance, identifying unused indexes, and optimizing query performance.
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 - Fetch index statistics
This query retrieves usage statistics for all indexes on the stores collection.
db.stores.aggregate([
{ $indexStats: {} }
])The query returns statistics for each index including access patterns and usage frequency.
[
{
"name": "_id_",
"key": { "_id": 1 },
"accesses": { "ops": 41675, "since": "2025-06-07T13:51:41.231Z" },
"spec": { "v": 2, "key": { "_id": 1 }, "name": "_id_" }
},
{
"name": "location_2dsphere",
"key": { "location": "2dsphere" },
"accesses": { "ops": 0, "since": "2025-06-07T13:51:41.231Z" },
"spec": {
"v": 2,
"key": { "location": "2dsphere" },
"name": "location_2dsphere",
"2dsphereIndexVersion": 3
}
},
{
"name": "name_text_sales.salesByCategory.categoryName_text_promotionEvents.eventName_text_promotionEvents.discounts.categoryName_text",
"key": {
"name": "text",
"sales.salesByCategory.categoryName": "text",
"promotionEvents.eventName": "text",
"promotionEvents.discounts.categoryName": "text"
},
"accesses": { "ops": 8, "since": "2025-06-07T13:51:41.231Z" },
"spec": {
"v": 2,
"key": {
"name": "text",
"sales.salesByCategory.categoryName": "text",
"promotionEvents.eventName": "text",
"promotionEvents.discounts.categoryName": "text"
},
"name": "name_text_sales.salesByCategory.categoryName_text_promotionEvents.eventName_text_promotionEvents.discounts.categoryName_text"
}
}
]