Use DynamoDBVersionAttribute when creating a new DynamoDB Table in Java - amazon-web-services

Question

I'm trying to add a DynamoDBVersionAttribute to incorporate optimistic locking when accessing/updating items in a DynamoDB table. However, I'm unable to figure out how exactly to add the version attribute.
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.OptimisticLocking.html seems to state that using it as an annotation in the class that creates the table is the way to go. However, our codebase is creating new tables in a format similar to this:
AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard().build();
DynamoDB dynamoDB = new DynamoDB(client);
List<AttributeDefinition> attributeDefinitions= new
ArrayList<AttributeDefinition>();
attributeDefinitions.add(new
AttributeDefinition().withAttributeName("Id").withAttributeType("N"));
List<KeySchemaElement> keySchema = new ArrayList<KeySchemaElement>();
keySchema.add(new
KeySchemaElement().withAttributeName("Id").withKeyType(KeyType.HASH));
CreateTableRequest request = new CreateTableRequest()
.withTableName(tableName)
.withKeySchema(keySchema)
.withAttributeDefinitions(attributeDefinitions)
.withProvisionedThroughput(new ProvisionedThroughput()
.withReadCapacityUnits(5L)
.withWriteCapacityUnits(6L));
Table table = dynamoDB.createTable(request);
I'm not able to find out how to add the VersionAttribute through the Java code as described above. It's not an attribute definitions so unsure where it goes. Any guidance as to where I can add this VersionAttribute in the CreateTable request?

Answer 1

As far as I'm aware, the #DynamoDBVersionAttribute annotation for optimistic locking is only available for tables modeled specifically for DynamoDBMapper queries. Using DynamoDBMapper is not a terrible approach, since it effectively creates an ORM for CRUD operations on DynamoDB items.
But if your existing codebase can't make use of it, your next best bet is probably to use conditional writes to increment a version number if it's equal to what you expect it to be (i.e. roll your own optimistic locking). Unfortunately, you would need to include the increment / condition to every write you want to be optimistically locked.

Answer 2

Your code just creates a table, but then in order to use DynamoDBMapper to access that table, you need to create a class that represents it. For example if your table is called Users, you should create a class called Users, and use annotations to link it to the table.
You can keep your table creation code, but you need to create the DynamoDBMapper class. You can then do all of your loading, saving and querying using the DynamoDBMapper class.
When you have created the class, just give it a field called version and put the annotation on it, DynamoDBMapper will take care of the rest.