PolarDB:Use document database (MongoDB-compatible)

mongosh client

1. Install the mongosh client: mongosh is the official command-line tool recommended by MongoDB. This topic uses an ECS instance running Alibaba Cloud Linux release 3 as an example.

   1. Run the following command to create a YUM repository file.

      sudo vim /etc/yum.repos.d/mongodb-org-6.repo

   2. Paste the following content into the file.

      [mongodb-org-6.0]
      name=MongoDB Repository
      baseurl=https://repo.mongodb.org/yum/redhat/8/mongodb-org/6.0/x86_64/
      gpgcheck=1
      enabled=1
      gpgkey=https://pgp.mongodb.com/server-6.0.asc

   3. Run the following installation command.

      sudo yum install -y mongodb-org

2. Connect to the database: Use the following command format and replace the placeholders with your actual values.

   mongosh "mongodb://<username>:<password>@<polardb_endpoint>:<port>"

   Parameters:

   • <username>: the document database account name.

   • <password>: the password for the document database account. If the password contains special characters such as @, #, or $, URL-encode the password first to prevent parsing errors in the connection string.

   • <polardb_endpoint>: the document database endpoint.

   • <port>: the port number for the document database endpoint.

   Connection example:

   # Assume the account is doc_user, the password is YourPassword123!, the endpoint is pe-****************.rwlb.rds.aliyuncs.com, and the port is 3306
   mongosh "mongodb://doc_user:YourPassword123!@pe-****************.rwlb.rds.aliyuncs.com:3306"

   After a successful connection, the command prompt changes to test> or a similar format.

3. Verify read and write operations.

   1. Run the following command to insert multiple documents.

      db.users.insertMany([
        { name: "Alice", age: 25, email: "alice@example.com" },
        { name: "Bob", age: 30, email: "bob@example.com" },
        { name: "Charlie", age: 22, email: "charlie@example.com" }
      ])

      If the operation is successful, the system returns a confirmation message and the ObjectId values of the inserted documents.

      {
        acknowledged: true,
        insertedIds: {
          '0': ObjectId('6926c9a36625af7c339xxx'),
          '1': ObjectId('6926c9a36625af7c339xxx'),
          '2': ObjectId('6926c9a36625af7c339xxx')
        }
      }

   2. Run the following command to query the inserted data.

      db.users.find({
        age: {
          $gt: 25 
        } 
      })

      If the record for Bob is returned, the document database compatibility feature is enabled and configured correctly for the PolarDB for MySQL cluster. Read and write operations are working as expected.

      [
        {
          name: 'Bob',
          age: 30,
          email: 'bob@example.com',
          _id: ObjectId('6926c9a36625af7c339xxx')
        }
      ]

Python example

Use the following Python sample code with the pymongo SDK to verify your configuration. This example uses an ECS instance running the Alibaba Cloud Linux 3.2104 LTS 64-bit operating system.

1. Go to your project directory as needed. This example uses /home/testMongoDB.

   mkdir /home/testMongoDB
   cd /home/testMongoDB

2. In the /home/testMongoDB directory, create a virtual environment (venv) to isolate project dependencies and avoid global pollution.

   python3 -m venv myenv

3. Activate the virtual environment.

   source myenv/bin/activate

4. Install the required Python dependencies.

   pip3 install pymongo

5. Create a Python file and copy the following code into it. Replace endpoint_url, username, and password with the document database endpoint and dedicated document database account of your PolarDB cluster.

   vim main.py

   from pymongo import MongoClient
   
   # 1. Configure your connection details
   # Endpoint URL from Step 2
   endpoint_url = "mongodb://<your-polardb-documentdb-endpoint>:<port>"
   # username from Step 3
   username = "<your-username>"
   # password from Step 3
   password = "<your-password>"
   
   
   def insert_data(userinfo):
       """Insert data into collection"""
       users = [
           {"_id": 1, "userid": "user01", "name": "Alice", "age": 18},
           {"_id": 2, "userid": "user02", "name": "Bob", "age": 25},
           {"_id": 3, "userid": "user03", "name": "Charlie", "age": 20},
       ]
       userinfo.insert_many(users)
       print("Inserted %d documents into the collection" % len(users))
   
   
   def find_data(userinfo):
       """Find data from collection"""
       users = userinfo.find()
       print("Found user info from collection")
       for user in users:
           print(user)
   
   
   def find_data_by_age(userinfo):
       """Find data by age from collection"""
       users = userinfo.find({"age": {"$gte": 20}})
       print("Found user info with age >= 20 from collection")
       for user in users:
           print(user)
   
   
   # Run the verification process
   if __name__ == "__main__":
       try:
           # 2. Create a MongoDB client
           client = MongoClient(endpoint_url, username=username, password=password)
           print("Connected to PolarDB DocumentDB successfully")
   
           database = client.get_database("test")
           userinfo = database.get_collection("userinfo")
   
           # 3. Insert some data and verify it
           insert_data(userinfo)
           find_data(userinfo)
           find_data_by_age(userinfo)
   
       finally:
           # Ensure the collection is cleaned up even if errors occur
           userinfo.drop()
           print("Collection deleted successfully")
           client.close()

6. After you run the script, you should see output similar to the following:

   python3 main.py

   Connected to PolarDB DocumentDB successfully
   Inserted 3 documents into the collection
   Found user info from collection
   {'_id': 1, 'userid': 'user01', 'name': 'Alice', 'age': 18}
   {'_id': 2, 'userid': 'user02', 'name': 'Bob', 'age': 25}
   {'_id': 3, 'userid': 'user03', 'name': 'Charlie', 'age': 20}
   Found user info with age >= 20 from collection
   {'_id': 2, 'userid': 'user02', 'name': 'Bob', 'age': 25}
   {'_id': 3, 'userid': 'user03', 'name': 'Charlie', 'age': 20}
   Collection deleted successfully

   This output indicates that you have successfully connected to and operated the document database. All configurations are in effect.