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APPLIES TO:
MongoDB vCore
The $match
stage in the aggregation pipeline is used to filter documents that match a specified condition. It's similar to the find
operation but is used within the aggregation pipeline to narrow down the documents that pass through to the next stage. This stage is highly useful for optimizing performance by reducing the number of documents that need to be processed in subsequent stages.
The basic syntax for the $match
stage is as follows:
{
$match: {
<query>
}
}
Description | |
---|---|
<query> |
A standard MongoDB query document that specifies the conditions that the documents must meet. |
Let's understand the usage with the following sample json.
{
"_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
"name": "Lakeshore Retail | DJ Equipment Stop - Port Cecile",
"location": {
"lat": 60.1441,
"lon": -141.5012
},
"staff": {
"totalStaff": {
"fullTime": 2,
"partTime": 0
}
},
"sales": {
"salesByCategory": [
{
"categoryName": "DJ Headphones",
"totalSales": 35921
}
],
"fullSales": 3700
},
"promotionEvents": [
{
"eventName": "Bargain Blitz Days",
"promotionalDates": {
"startDate": {
"Year": 2024,
"Month": 3,
"Day": 11
},
"endDate": {
"Year": 2024,
"Month": 2,
"Day": 18
}
},
"discounts": [
{
"categoryName": "DJ Turntables",
"discountPercentage": 18
},
{
"categoryName": "DJ Mixers",
"discountPercentage": 15
}
]
}
],
"tag": [
"#ShopLocal",
"#SeasonalSale",
"#FreeShipping",
"#MembershipDeals"
]
}
To filter documents where the _id
is "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5":
db.stores.aggregate([
{
$match: {
"_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5"
}
}
])
This query would return the sample document.
To filter documents where the total sales are greater than $35,000:
db.stores.aggregate([
{
$match: {
"sales.totalSales": { $gt: 35000 }
}
},
// Limit the result to the first 3 documents
{ $limit: 3 },
// Include only _id and name fields in the output
{ $project: { _id: 1, name: 1 } }
])
This query would return the following document.
[
{
"_id": "8345de34-73ec-4a99-9cb6-a81f7b145c34",
"name": "Northwind Traders | Bed and Bath Place - West Oraland"
},
{
"_id": "57cc4095-77d9-4345-af20-f8ead9ef0197",
"name": "Wide World Importers | Bed and Bath Store - West Vitafort"
},
{
"_id": "560099f8-325f-4c35-a4e5-2e0879eb95af",
"name": "Wide World Importers | Bed and Bath Depot - North Maritzaberg"
}
]
To filter documents where there's a discount of 15% on DJ Mixers:
db.stores.aggregate([
{
$match: {
"promotionEvents.discounts": {
$elemMatch: {
"categoryName": "DJ Mixers",
"discountPercentage": 15
}
}
}
},
// Limit the result to the first 3 documents
{ $limit: 3 },
// Include only _id and name fields in the output
{ $project: { _id: 1, name: 1 } }
])
This query would return the following document.
[
{
"_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
"name": "Lakeshore Retail | DJ Equipment Stop - Port Cecile"
},
{
"_id": "3c7eda41-23a1-4226-abf6-17ee9e851b5b",
"name": "Boulder Innovations | DJ Equipment Bazaar - New Ceasarview"
},
{
"_id": "63831a7d-13a9-4d8b-bf1d-ac004057f96d",
"name": "Contoso, Ltd. | DJ Equipment Shop - Reillyfurt"
}
]
- Review options for Migrating from MongoDB to Azure Cosmos DB for MongoDB (vCore)
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