Querying Global Secondary Indexes with SDK for Java 1.x - Amazon DynamoDB

Querying Global Secondary Indexes with SDK for Java 1.x

You can use Amazon DynamoDB Accelerator (DAX) to query global secondary indexes using DynamoDB programmatic interfaces.

The following example demonstrates how to use DAX to query the CreateDateIndex global secondary index that is created in Example: Global Secondary Indexes Using the AWS SDK for Java Document API.

The DAXClient class instantiates the client objects that are needed to interact with the DynamoDB programming interfaces.

import com.amazon.dax.client.dynamodbv2.AmazonDaxClientBuilder; import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper; import com.amazonaws.services.dynamodbv2.document.DynamoDB; import com.amazonaws.util.EC2MetadataUtils; import com.amazonaws.services.dynamodbv2.AmazonDynamoDB; public class DaxClient { private static final String region = EC2MetadataUtils.getEC2InstanceRegion(); DynamoDB getDaxDocClient(String daxEndpoint) { System.out.println("Creating a DAX client with cluster endpoint " + daxEndpoint); AmazonDaxClientBuilder daxClientBuilder = AmazonDaxClientBuilder.standard(); daxClientBuilder.withRegion(region).withEndpointConfiguration(daxEndpoint); AmazonDynamoDB client = daxClientBuilder.build(); return new DynamoDB(client); } DynamoDBMapper getDaxMapperClient(String daxEndpoint) { System.out.println("Creating a DAX client with cluster endpoint " + daxEndpoint); AmazonDaxClientBuilder daxClientBuilder = AmazonDaxClientBuilder.standard(); daxClientBuilder.withRegion(region).withEndpointConfiguration(daxEndpoint); AmazonDynamoDB client = daxClientBuilder.build(); return new DynamoDBMapper(client); } }

You can query a global secondary index in the following ways:

  • Use the queryIndex method on the QueryIndexDax class defined in the following example. The QueryIndexDax takes as a parameter the client object that is returned by the getDaxDocClient method on the DaxClient class.

  • If you are using the object persistence interface, use the queryIndexMapper method on the QueryIndexDax class defined in the following example. The queryIndexMapper takes as a parameter the client object that is returned by the getDaxMapperClient method defined on the DaxClient class.

import java.util.Iterator; import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper; import java.util.List; import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBQueryExpression; import com.amazonaws.services.dynamodbv2.model.AttributeValue; import java.util.HashMap; import com.amazonaws.services.dynamodbv2.document.Item; import com.amazonaws.services.dynamodbv2.document.utils.ValueMap; import com.amazonaws.services.dynamodbv2.document.spec.QuerySpec; import com.amazonaws.services.dynamodbv2.document.QueryOutcome; import com.amazonaws.services.dynamodbv2.document.ItemCollection; import com.amazonaws.services.dynamodbv2.document.Index; import com.amazonaws.services.dynamodbv2.document.Table; import com.amazonaws.services.dynamodbv2.document.DynamoDB; public class QueryIndexDax { //This is used to query Index using the low-level interface. public static void queryIndex(DynamoDB client, String tableName, String indexName) { Table table = client.getTable(tableName); System.out.println("\n***********************************************************\n"); System.out.print("Querying index " + indexName + "..."); Index index = table.getIndex(indexName); ItemCollection<QueryOutcome> items = null; QuerySpec querySpec = new QuerySpec(); if (indexName == "CreateDateIndex") { System.out.println("Issues filed on 2013-11-01"); querySpec.withKeyConditionExpression("CreateDate = :v_date and begins_with(IssueId, :v_issue)") .withValueMap(new ValueMap().withString(":v_date", "2013-11-01").withString(":v_issue", "A-")); items = index.query(querySpec); } else { System.out.println("\nNo valid index name provided"); return; } Iterator<Item> iterator = items.iterator(); System.out.println("Query: printing results..."); while (iterator.hasNext()) { System.out.println(iterator.next().toJSONPretty()); } } //This is used to query Index using the high-level mapper interface. public static void queryIndexMapper(DynamoDBMapper mapper, String tableName, String indexName) { HashMap<String, AttributeValue> eav = new HashMap<String, AttributeValue>(); eav.put(":v_date", new AttributeValue().withS("2013-11-01")); eav.put(":v_issue", new AttributeValue().withS("A-")); DynamoDBQueryExpression<CreateDate> queryExpression = new DynamoDBQueryExpression<CreateDate>() .withIndexName("CreateDateIndex").withConsistentRead(false) .withKeyConditionExpression("CreateDate = :v_date and begins_with(IssueId, :v_issue)") .withExpressionAttributeValues(eav); List<CreateDate> items = mapper.query(CreateDate.class, queryExpression); Iterator<CreateDate> iterator = items.iterator(); System.out.println("Query: printing results..."); while (iterator.hasNext()) { CreateDate iterObj = iterator.next(); System.out.println(iterObj.getCreateDate()); System.out.println(iterObj.getIssueId()); } } }

The class definition below represents the Issues table and is used in the queryIndexMapper method.

import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTable; import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBIndexHashKey; import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBIndexRangeKey; import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBHashKey; @DynamoDBTable(tableName = "Issues") public class CreateDate { private String createDate; @DynamoDBHashKey(attributeName = "IssueId") private String issueId; @DynamoDBIndexHashKey(globalSecondaryIndexName = "CreateDateIndex", attributeName = "CreateDate") public String getCreateDate() { return createDate; } public void setCreateDate(String createDate) { this.createDate = createDate; } @DynamoDBIndexRangeKey(globalSecondaryIndexName = "CreateDateIndex", attributeName = "IssueId") public String getIssueId() { return issueId; } public void setIssueId(String issueId) { this.issueId = issueId; } }