Batch Query in DynamoDB Using Java (Guide w/ Code Examples)

DynamoDB offers a batchGetItem method that allows you to retrieve multiple items from one or more tables in a single request.

In the snippet shown below, the batchGetItem method retrieves items from two tables: "Table1" and "Table2". All keys to that need to be retrieved are specified in the requestItems map. This maps table names to lists of item keys.

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;
import com.amazonaws.services.dynamodbv2.document.DynamoDB;
import com.amazonaws.services.dynamodbv2.document.TableKeysAndAttributes;
import com.amazonaws.services.dynamodbv2.model.BatchGetItemRequest;
import com.amazonaws.services.dynamodbv2.model.BatchGetItemResult;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class BatchGetExample {
    public static void main(String[] args) {
        // Create a new client
        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard().build();
        DynamoDB dynamoDB = new DynamoDB(client);

        // Create a map of table name to keys
        Map<String, List<Map<String, Object>>> requestItems = new HashMap<>();
        requestItems.put("Table1", Arrays.asList(new HashMap<String, Object>() {{
            put("id", "123");
        }},new HashMap<String, Object>() {{
            put("id", "456");
        }}));
        requestItems.put("Table2", Arrays.asList(new HashMap<String, Object>() {{
            put("id", "789");
        }},new HashMap<String, Object>() {{
            put("id", "555");
        }}));
        
        TableKeysAndAttributes tka = new TableKeysAndAttributes("Table1");
        tka.addHashAndRangePrimaryKey("id", "123", "id", "456");
        tka.addHashAndRangePrimaryKey("id", "789", "id", "555");
        
        BatchGetItemRequest request = new BatchGetItemRequest()
                .withRequestItems(requestItems)
                .withReturnConsumedCapacity(ReturnConsumedCapacity.TOTAL);
        
        BatchGetItemResult result = client.batchGetItem(request);
        // process the result
    }
}