示例:使用 Amazon SDK for Java 文档 API 创建全局二级索引 - Amazon DynamoDB
Amazon Web Services 文档中描述的 Amazon Web Services 服务或功能可能因区域而异。要查看适用于中国区域的差异,请参阅 中国的 Amazon Web Services 服务入门 (PDF)

本文属于机器翻译版本。若本译文内容与英语原文存在差异,则一律以英文原文为准。

示例:使用 Amazon SDK for Java 文档 API 创建全局二级索引

以下 Java 代码示例显示如何处理全局二级索引。本示例创建了一个 Issues 表,可以用于软件开发的简单错误跟踪系统。分区键为 IssueId,排序键为 Title。此表上有 3 个全局二级索引:

  • CreateDateIndex — 分区键为 CreateDate,排序键为 IssueId。除了表键之外,属性 DescriptionStatus 投影到索引中。

  • TitleIndex — 分区键为 Title,排序键为 IssueId。表键以外的其他属性都不投影到索引中。

  • DueDateIndex — 分区键为 DueDate;没有排序键。所有表属性都投影到索引中。

创建 Issues 表后,程序为该表加载表示软件问题报告的数据。然后使用全局二级索引查询这些数据。最后,程序会删除 Issues 表。

有关测试以下示例的 step-by-step 说明,请参阅Java 代码示例

package com.amazonaws.codesamples.document; import java.util.ArrayList; import java.util.Iterator; 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.Index; import com.amazonaws.services.dynamodbv2.document.Item; import com.amazonaws.services.dynamodbv2.document.ItemCollection; import com.amazonaws.services.dynamodbv2.document.QueryOutcome; import com.amazonaws.services.dynamodbv2.document.Table; import com.amazonaws.services.dynamodbv2.document.spec.QuerySpec; import com.amazonaws.services.dynamodbv2.document.utils.ValueMap; import com.amazonaws.services.dynamodbv2.model.AttributeDefinition; import com.amazonaws.services.dynamodbv2.model.CreateTableRequest; import com.amazonaws.services.dynamodbv2.model.GlobalSecondaryIndex; import com.amazonaws.services.dynamodbv2.model.KeySchemaElement; import com.amazonaws.services.dynamodbv2.model.KeyType; import com.amazonaws.services.dynamodbv2.model.Projection; import com.amazonaws.services.dynamodbv2.model.ProvisionedThroughput; public class DocumentAPIGlobalSecondaryIndexExample { static AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard().build(); static DynamoDB dynamoDB = new DynamoDB(client); public static String tableName = "Issues"; public static void main(String[] args) throws Exception { createTable(); loadData(); queryIndex("CreateDateIndex"); queryIndex("TitleIndex"); queryIndex("DueDateIndex"); deleteTable(tableName); } public static void createTable() { // Attribute definitions ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<AttributeDefinition>(); attributeDefinitions.add(new AttributeDefinition().withAttributeName("IssueId").withAttributeType("S")); attributeDefinitions.add(new AttributeDefinition().withAttributeName("Title").withAttributeType("S")); attributeDefinitions.add(new AttributeDefinition().withAttributeName("CreateDate").withAttributeType("S")); attributeDefinitions.add(new AttributeDefinition().withAttributeName("DueDate").withAttributeType("S")); // Key schema for table ArrayList<KeySchemaElement> tableKeySchema = new ArrayList<KeySchemaElement>(); tableKeySchema.add(new KeySchemaElement().withAttributeName("IssueId").withKeyType(KeyType.HASH)); // Partition // key tableKeySchema.add(new KeySchemaElement().withAttributeName("Title").withKeyType(KeyType.RANGE)); // Sort // key // Initial provisioned throughput settings for the indexes ProvisionedThroughput ptIndex = new ProvisionedThroughput().withReadCapacityUnits(1L) .withWriteCapacityUnits(1L); // CreateDateIndex GlobalSecondaryIndex createDateIndex = new GlobalSecondaryIndex().withIndexName("CreateDateIndex") .withProvisionedThroughput(ptIndex) .withKeySchema(new KeySchemaElement().withAttributeName("CreateDate").withKeyType(KeyType.HASH), // Partition // key new KeySchemaElement().withAttributeName("IssueId").withKeyType(KeyType.RANGE)) // Sort // key .withProjection( new Projection().withProjectionType("INCLUDE").withNonKeyAttributes("Description", "Status")); // TitleIndex GlobalSecondaryIndex titleIndex = new GlobalSecondaryIndex().withIndexName("TitleIndex") .withProvisionedThroughput(ptIndex) .withKeySchema(new KeySchemaElement().withAttributeName("Title").withKeyType(KeyType.HASH), // Partition // key new KeySchemaElement().withAttributeName("IssueId").withKeyType(KeyType.RANGE)) // Sort // key .withProjection(new Projection().withProjectionType("KEYS_ONLY")); // DueDateIndex GlobalSecondaryIndex dueDateIndex = new GlobalSecondaryIndex().withIndexName("DueDateIndex") .withProvisionedThroughput(ptIndex) .withKeySchema(new KeySchemaElement().withAttributeName("DueDate").withKeyType(KeyType.HASH)) // Partition // key .withProjection(new Projection().withProjectionType("ALL")); CreateTableRequest createTableRequest = new CreateTableRequest().withTableName(tableName) .withProvisionedThroughput( new ProvisionedThroughput().withReadCapacityUnits((long) 1).withWriteCapacityUnits((long) 1)) .withAttributeDefinitions(attributeDefinitions).withKeySchema(tableKeySchema) .withGlobalSecondaryIndexes(createDateIndex, titleIndex, dueDateIndex); System.out.println("Creating table " + tableName + "..."); dynamoDB.createTable(createTableRequest); // Wait for table to become active System.out.println("Waiting for " + tableName + " to become ACTIVE..."); try { Table table = dynamoDB.getTable(tableName); table.waitForActive(); } catch (InterruptedException e) { e.printStackTrace(); } } public static void queryIndex(String indexName) { Table table = dynamoDB.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 if (indexName == "TitleIndex") { System.out.println("Compilation errors"); querySpec.withKeyConditionExpression("Title = :v_title and begins_with(IssueId, :v_issue)") .withValueMap( new ValueMap().withString(":v_title", "Compilation error").withString(":v_issue", "A-")); items = index.query(querySpec); } else if (indexName == "DueDateIndex") { System.out.println("Items that are due on 2013-11-30"); querySpec.withKeyConditionExpression("DueDate = :v_date") .withValueMap(new ValueMap().withString(":v_date", "2013-11-30")); 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()); } } public static void deleteTable(String tableName) { System.out.println("Deleting table " + tableName + "..."); Table table = dynamoDB.getTable(tableName); table.delete(); // Wait for table to be deleted System.out.println("Waiting for " + tableName + " to be deleted..."); try { table.waitForDelete(); } catch (InterruptedException e) { e.printStackTrace(); } } public static void loadData() { System.out.println("Loading data into table " + tableName + "..."); // IssueId, Title, // Description, // CreateDate, LastUpdateDate, DueDate, // Priority, Status putItem("A-101", "Compilation error", "Can't compile Project X - bad version number. What does this mean?", "2013-11-01", "2013-11-02", "2013-11-10", 1, "Assigned"); putItem("A-102", "Can't read data file", "The main data file is missing, or the permissions are incorrect", "2013-11-01", "2013-11-04", "2013-11-30", 2, "In progress"); putItem("A-103", "Test failure", "Functional test of Project X produces errors", "2013-11-01", "2013-11-02", "2013-11-10", 1, "In progress"); putItem("A-104", "Compilation error", "Variable 'messageCount' was not initialized.", "2013-11-15", "2013-11-16", "2013-11-30", 3, "Assigned"); putItem("A-105", "Network issue", "Can't ping IP address 127.0.0.1. Please fix this.", "2013-11-15", "2013-11-16", "2013-11-19", 5, "Assigned"); } public static void putItem( String issueId, String title, String description, String createDate, String lastUpdateDate, String dueDate, Integer priority, String status) { Table table = dynamoDB.getTable(tableName); Item item = new Item().withPrimaryKey("IssueId", issueId).withString("Title", title) .withString("Description", description).withString("CreateDate", createDate) .withString("LastUpdateDate", lastUpdateDate).withString("DueDate", dueDate) .withNumber("Priority", priority).withString("Status", status); table.putItem(item); } }