AWS documentdb documentation change

Service: documentdb · 2026-03-31 · Documentation low

File: documentdb/latest/developerguide/addToSet-aggregation.md

Summary

Added new documentation page for the $addToSet aggregation operator in Amazon DocumentDB, including syntax, parameters, MongoDB shell example, and code examples in Node.js and Python with connection details

Security assessment

This change adds documentation for a database aggregation operator ($addToSet) with code examples that include secure connection parameters (TLS=true, tlsCAFile=global-bundle.pem). While the documentation includes security best practices for connecting to DocumentDB, there is no evidence this addresses a specific security vulnerability or incident. The change appears to be routine feature documentation.

Diff

diff --git a/documentdb/latest/developerguide/addToSet-aggregation.md b/documentdb/latest/developerguide/addToSet-aggregation.md
index 8b1378917..c859a9d25 100644
--- a//documentdb/latest/developerguide/addToSet-aggregation.md
+++ b//documentdb/latest/developerguide/addToSet-aggregation.md
@@ -0,0 +1 @@
+[](/pdfs/documentdb/latest/developerguide/developerguide.pdf#addToSet-aggregation "Open PDF")
@@ -1,0 +3,126 @@
+[Documentation](/index.html)[Amazon DocumentDB](/documentdb/index.html)[Developer Guide](what-is.html)
+
+Example (MongoDB Shell)Code examples
+
+# $addToSet
+
+The `$addToSet` aggregation operator returns an array of unique values from a specified expression for each group. It is used within the `$group` stage to accumulate distinct values, automatically eliminating duplicates.
+
+**Parameters**
+
+  * `expression`: The expression to evaluate for each document in the group.
+
+
+
+
+## Example (MongoDB Shell)
+
+The following example demonstrates using the `$addToSet` operator to collect unique cities where orders were placed for each customer.
+
+**Create sample documents**
+    
+    
+    db.orders.insertMany([
+      { _id: 1, customer: "Alice", city: "Seattle", amount: 100 },
+      { _id: 2, customer: "Alice", city: "Portland", amount: 150 },
+      { _id: 3, customer: "Bob", city: "Seattle", amount: 200 },
+      { _id: 4, customer: "Alice", city: "Seattle", amount: 75 },
+      { _id: 5, customer: "Bob", city: "Boston", amount: 300 }
+    ]);
+
+**Query example**
+    
+    
+    db.orders.aggregate([
+      {
+        $group: {
+          _id: "$customer",
+          cities: { $addToSet: "$city" }
+        }
+      }
+    ]);
+
+**Output**
+    
+    
+    [
+      { _id: 'Bob', cities: [ 'Seattle', 'Boston' ] },
+      { _id: 'Alice', cities: [ 'Seattle', 'Portland' ] }
+    ]
+
+## Code examples
+
+To view a code example for using the `$addToSet` aggregation operator, choose the tab for the language that you want to use:
+
+Node.js
+    
+    
+    
+    const { MongoClient } = require('mongodb');
+    
+    async function example() {
+      const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
+      const db = client.db('test');
+      const collection = db.collection('orders');
+    
+      const result = await collection.aggregate([
+        {
+          $group: {
+            _id: "$customer",
+            cities: { $addToSet: "$city" }
+          }
+        }
+      ]).toArray();
+    
+      console.log(result);
+      await client.close();
+    }
+    
+    example();
+
+Python
+    
+    
+    
+    from pymongo import MongoClient
+    
+    def example():
+        client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
+        db = client['test']
+        collection = db['orders']
+    
+        result = list(collection.aggregate([
+            {
+                '$group': {
+                    '_id': '$customer',
+                    'cities': { '$addToSet': '$city' }
+                }
+            }
+        ]))
+    
+        print(result)
+        client.close()
+    
+    example()
+
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+
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+
+[Document Conventions](/general/latest/gr/docconventions.html)
+
+$add
+
+$addFields
+
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