How to make a UUID in DynamoDB?

For those coding in Java, DynamoDBMapper can now generate unique UUIDs on your behalf.

DynamoDBAutoGeneratedKey

Marks a partition key or sort key property as being auto-generated. DynamoDBMapper will generate a random UUID when saving these attributes. Only String properties can be marked as auto-generated keys.

Use the DynamoDBAutoGeneratedKey annotation like this

@DynamoDBTable(tableName="AutoGeneratedKeysExample")
public class AutoGeneratedKeys { 
    private String id;

    @DynamoDBHashKey(attributeName = "Id")
    @DynamoDBAutoGeneratedKey
    public String getId() { return id; }
    public void setId(String id) { this.id = id; } 

As you can see in the example above, you can apply both the DynamoDBAutoGeneratedKey and DynamoDBHashKey annotation to the same attribute to generate a unique hash key.

Auto Increment is not good from performance perspective as it will overload specific shards while keeping others idle, It doesn't make even distribution if you're storing data to Dynamodb.

awsRequestId looks like its actually V.4 UUID (Random), code snippet below to try it:

exports.handler = function(event, context, callback) {
    console.log('remaining time =', context.getRemainingTimeInMillis());
    console.log('functionName =', context.functionName);
    console.log('AWSrequestID =', context.awsRequestId);
    callback(null, context.functionName);
};

In case you want to generate this yourself, you can use https://www.npmjs.com/package/uuid or Ulide to generate different versions of UUID based on RFC-4122

• V1 (timestamp based)
• V3 (Namespace)
• V4 (Random)

For Go developers, you can use these packages from Google's UUID, Pborman, or Satori. Pborman is better in performance, check these articles and benchmarks for more details.

More Info on Universal Unique Identifier Specification could be found here.

Incase you are using NoSQL DynamoDB then using Dynamoose ORM, you can easily set default unique id. Here is the simple user creation example

// User.modal.js

const dynamoose = require("dynamoose");

const userSchema = new dynamoose.Schema(
  {
    id: {
      type: String,
      hashKey: true,
    },
    displayName: String,
    firstName: String,
    lastName: String,
  },
  { timestamps: true },
);

const User = dynamoose.model("User", userSchema);

module.exports = User;

// User.controller.js

const { v4: uuidv4 } = require("uuid");    
const User = require("./user.model");

exports.create = async (req, res) => {
  const user = new User({ id: uuidv4(), ...req.body }); // set unique id
  const [err, response] = await to(user.save());
  if (err) {
    return badRes(res, err);
  }
  return goodRes(res, reponse);
};