java实现DynamoDB创表[全局索引]

什么是Amazon DynamoDB？

Amazon DynamoDB 是一种完全托管的 NoSQL 数据库服务。

Amazon DynamoDB有哪些核心组件？

Amazon DynamoDB的核心组件有三个：表（Table）、项目（Item）、属性（Attribute）。

Table、Item、Attribute组件之间有什么关系？

举个栗子：结合你使用的关系型数据库进行理解，Table指的表就不用说了，Item相当于表中的一个对象（一行数据），Attribute就是对象的每个属性（每一列）。

总的来说就是：item是attribute的集合，table是item的集合。

创表时需要设置主键，唯一标识每一个项目，同时可设置多个排序键以及本地索引和全局二级索引。

欲知更多，请疯狂点击访问官网：Amazon DynamoDB官方文档

以下是创表的具体实现：SpringBoot采用2.2.3版本。

一、 Maven依赖

<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>com.amazonaws</groupId>
				<artifactId>aws-java-sdk-bom</artifactId>
				<version>1.11.710</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>com.github.derjust</groupId>
			<artifactId>spring-data-dynamodb</artifactId>
			<version>5.0.4</version>
		</dependency>
		<dependency>
			<groupId>com.amazonaws</groupId>
			<artifactId>aws-java-sdk-dynamodb</artifactId>
		</dependency>

		<dependency>
			<groupId>com.amazonaws</groupId>
			<artifactId>aws-java-sdk-iot</artifactId>
		</dependency>
	</dependencies>

二、创表

    /**
     * create global index table
     *
     * @return
     * @throws Exception
     */
    @PostMapping("/createGlobalIndexTable")
    public ResponseEntity<String> createGlobalIndexTable() throws Exception {
        // 表名
        String tableName = "testOnly";
        // 属性定义
        ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<AttributeDefinition>();
        attributeDefinitions.add(new AttributeDefinition().withAttributeName("id").withAttributeType("S"));
        attributeDefinitions.add(new AttributeDefinition().withAttributeName("name").withAttributeType("S"));
        attributeDefinitions.add(new AttributeDefinition().withAttributeName("email").withAttributeType("S"));
        // Key schema for table
        ArrayList<KeySchemaElement> tableKeySchema = new ArrayList<KeySchemaElement>();
        // 分区键
        tableKeySchema.add(new KeySchemaElement().withAttributeName("id").withKeyType(KeyType.HASH)); // Partition
        // 排序键
        tableKeySchema.add(new KeySchemaElement().withAttributeName("email").withKeyType(KeyType.RANGE)); // Sort
        // Initial provisioned throughput settings for the indexes
        ProvisionedThroughput ptIndex = new ProvisionedThroughput().withReadCapacityUnits(1L)
                .withWriteCapacityUnits(1L);
        // 全局二级索引
        GlobalSecondaryIndex createEmailIndex = new GlobalSecondaryIndex().withIndexName("GlobalEmailIndex")
                .withProvisionedThroughput(ptIndex)
                .withKeySchema(new KeySchemaElement().withAttributeName("email").withKeyType(KeyType.HASH), // Partition
                        // key
                        new KeySchemaElement().withAttributeName("name").withKeyType(KeyType.RANGE)) // Sort
                // 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(createEmailIndex);

        TableUtils.createTableIfNotExists(dynamoDB, createTableRequest);
        TableUtils.waitUntilActive(dynamoDB, tableName);

        return new ResponseEntity<>(HttpStatus.OK);
    }