Insert Items to DynamoDB Tables using Java

Emmanouil GkatziourasJune 29th, 2016Last Updated: June 28th, 2016

1 80 1 minute read

On a previous article we learned how to create DynamoDB Tables using Java. Next step is to insert items to the DynamoDB Tables previously created.

Keep in mind that for the insert action the most basic step is to specify the the primary key. For the table users the primary key is the attribute email. You can add as many attributes as you want however the cumulative size should not surpass 400 KB.

Map<String,AttributeValue> attributeValues = new HashMap<>();
        attributeValues.put("email",new AttributeValue().withS("jon@doe.com"));
        attributeValues.put("fullname",new AttributeValue().withS("Jon Doe"));

        PutItemRequest putItemRequest = new PutItemRequest()
                .withTableName("Users")
                .withItem(attributeValues);

        PutItemResult putItemResult = amazonDynamoDB.putItem(putItemRequest);

DynamoDB also supports Batch writes. In this case the main benefit lies on less I/O, however nothing changes regarding consumed capacity. In our case we will add a batch of login attempts.

Map<String,AttributeValue> firstAttributeValues = new HashMap<>();
        firstAttributeValues.put("email",new AttributeValue().withS("jon@doe.com"));

        Long date = new Date().getTime();

        firstAttributeValues.put("timestamp",new AttributeValue().withN(Long.toString(date)));

        PutRequest firstPutRequest = new PutRequest();
        firstPutRequest.setItem(firstAttributeValues);

        WriteRequest firstWriteRequest = new WriteRequest();
        firstWriteRequest.setPutRequest(firstPutRequest);


        Map<String,AttributeValue> secondAttributeValues = new HashMap<>();
        secondAttributeValues.put("email",new AttributeValue().withS("jon@doe.com"));
        secondAttributeValues.put("timestamp",new AttributeValue().withN(Long.toString(date+100)));

        PutRequest secondPutRequest = new PutRequest();
        secondPutRequest.setItem(secondAttributeValues);

        WriteRequest secondWriteRequest = new WriteRequest();
        secondWriteRequest.setPutRequest(secondPutRequest);

        List<WriteRequest> batchList = new ArrayList<WriteRequest>();
        batchList.add(firstWriteRequest);
        batchList.add(secondWriteRequest);

        Map<String, List<WriteRequest>> batchTableRequests = new HashMap<String, List<WriteRequest>>();
        batchTableRequests.put("Logins",batchList);

        BatchWriteItemRequest batchWriteItemRequest = new BatchWriteItemRequest();
        batchWriteItemRequest.setRequestItems(batchTableRequests);

        amazonDynamoDB.batchWriteItem(batchWriteItemRequest);

In case of an insert with a global/local secondary index all you have to do is to specify the corresponding attributes for the index. Take into consideration that you can have empty index related attributes or even duplicates.

Map<String,AttributeValue> attributeValues = new HashMap<>();
        attributeValues.put("name",new AttributeValue().withS("Random SuperVisor"));
        attributeValues.put("company",new AttributeValue().withS("Random Company"));
        attributeValues.put("factory",new AttributeValue().withS("Jon Doe"));


        PutItemRequest putItemRequest = new PutItemRequest()
                .withTableName("Supervisors")
                .withItem(attributeValues);

        PutItemResult putItemResult = amazonDynamoDB.putItem(putItemRequest);

You can find the sourcecode on github.

Reference:

Insert Items to DynamoDB Tables using Java from our JCG partner Emmanouil Gkatziouras at the gkatzioura blog.