AWS documentdb documentation change

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

File: documentdb/latest/developerguide/setUnion.md

Summary

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

Security assessment

This change adds routine documentation for a database aggregation operator ($setUnion) with standard usage examples. The code examples include TLS connection parameters (tls=true, tlsCAFile=global-bundle.pem) which are standard security practices for DocumentDB connections, but this is not new security documentation - it's just showing standard secure connection setup. There is no evidence this addresses a specific security vulnerability, weakness, or incident.

Diff

diff --git a/documentdb/latest/developerguide/setUnion.md b/documentdb/latest/developerguide/setUnion.md
index 8b1378917..e27f1e48e 100644
--- a//documentdb/latest/developerguide/setUnion.md
+++ b//documentdb/latest/developerguide/setUnion.md
@@ -0,0 +1 @@
+[](/pdfs/documentdb/latest/developerguide/developerguide.pdf#setUnion "Open PDF")
@@ -1,0 +3,133 @@
+[Documentation](/index.html)[Amazon DocumentDB](/documentdb/index.html)[Developer Guide](what-is.html)
+
+Example (MongoDB Shell)Code examples
+
+# $setUnion
+
+The `$setUnion` aggregation operator in Amazon DocumentDB is used to combine two or more sets of values and return a set that contains all the unique elements from the input sets. This operator is useful when you need to perform set-based operations on array fields in your documents.
+
+**Parameters**
+
+  * `expression1`: An expression that resolves to an array.
+
+  * `expression2`: An expression that resolves to an array.
+
+  * `expressionN`: Additional expressions that resolve to arrays (optional).
+
+
+
+
+## Example (MongoDB Shell)
+
+The following example demonstrates how to use the `$setUnion` operator to combine the unique elements from two array fields in a collection.
+
+**Create sample documents**
+    
+    
+    db.users.insertMany([
+      { _id: 1, name: "Alice", hobbies: ["reading", "swimming"], skills: ["coding", "writing"] },
+      { _id: 2, name: "Bob", hobbies: ["cooking", "gardening"], skills: ["coding", "photography"] },
+      { _id: 3, name: "Charlie", hobbies: ["reading", "painting"], skills: ["gardening", "music"] }
+    ]);
+
+**Query example**
+    
+    
+    db.users.aggregate([
+      {
+        $project: {
+          name: 1,
+          allInterests: { $setUnion: ["$hobbies", "$skills"] }
+        }
+      }
+    ]);
+
+**Output**
+    
+    
+    [
+      { "_id" : 1, "name" : "Alice", "allInterests" : [ "coding", "reading", "swimming", "writing" ] },
+      { "_id" : 2, "name" : "Bob", "allInterests" : [ "coding", "cooking", "gardening", "photography" ] },
+      { "_id" : 3, "name" : "Charlie", "allInterests" : [ "gardening", "music", "painting", "reading" ] }
+    ]
+
+In this example, the `$setUnion` operator is used to combine the unique elements from the `hobbies` and `skills` array fields for each user document. The resulting `allInterests` field contains the union of all the unique hobbies and skills for each user.
+
+## Code examples
+
+To view a code example for using the `$setUnion` command, 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 users = db.collection('users');
+    
+      const result = await users.aggregate([
+        {
+          $project: {
+            _id: 1,
+            name: 1,
+            allInterests: { $setUnion: ["$hobbies", "$skills"] }
+          }
+        }
+      ]).toArray();
+    
+      console.log(result);
+      await client.close();
+    }
+    
+    example();
+
+Python
+    
+    
+    
+    from pymongo import MongoClient
+    
+    def example():
+        client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
+        db = client['test']
+        users = db['users']
+    
+        result = list(users.aggregate([
+            {
+                '$project': {
+                    '_id': 1,
+                    'name': 1,
+                    'allInterests': { '$setUnion': ["$hobbies", "$skills"] }
+                }
+            }
+        ]))
+    
+        print(result)
+        client.close()
+    
+    example()
+
+![Warning](https://d1ge0kk1l5kms0.cloudfront.net/images/G/01/webservices/console/warning.png) **Javascript is disabled or is unavailable in your browser.**
+
+To use the Amazon Web Services Documentation, Javascript must be enabled. Please refer to your browser's Help pages for instructions.
+
+[Document Conventions](/general/latest/gr/docconventions.html)
+
+$setIsSubset
+
+$skip
+
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+
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+
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