java - 如何在 Android 中按升序对 DynamoDB Hashkey 进行排序

Question

我正在开发一个 Android 应用程序，我在其中创建一个带有“数字”哈希键的 DynamoDB 表。

public static void createTable() {

    Log.d(TAG, "Create table called");

    AmazonDynamoDBClient ddb = UserPreferenceDemoActivity.clientManager
            .ddb();

    KeySchemaElement kse = new KeySchemaElement().withAttributeName(
            "Tid").withKeyType(KeyType.HASH);
    AttributeDefinition ad = new AttributeDefinition().withAttributeName(
            "Tid").withAttributeType(ScalarAttributeType.N);

    ProvisionedThroughput pt = new ProvisionedThroughput()
            .withReadCapacityUnits(10l).withWriteCapacityUnits(5l);

    CreateTableRequest request = new CreateTableRequest()
            .withTableName(Constants.TEST_TABLE_NAME)
            .withKeySchema(kse).withAttributeDefinitions(ad)                               
            .withProvisionedThroughput(pt);

    try {
        Log.d(TAG, "Sending Create table request");
        ddb.createTable(request);
        Log.d(TAG, "Create request response successfully recieved");
    } catch (AmazonServiceException ex) {
        Log.e(TAG, "Error sending create table request", ex);
        UserPreferenceDemoActivity.clientManager
                .wipeCredentialsOnAuthError(ex);
    }
    insertUsers();
}

然后我最后调用 insertUsers() 方法，我将三个键值 (800,815,830) 添加到创建的表中:

 public static void insertUsers() {
    AmazonDynamoDBClient ddb = UserPreferenceDemoActivity.clientManager
            .ddb();
    DynamoDBMapper mapper = new DynamoDBMapper(ddb);

    try {
        for (int i = 1; i <= 3; i++) {
            UserPreference userPreference = new UserPreference();

            if (i == 1)
            {
             userPreference.setTid(800);                 
            }
            else if (i == 2)
            {
                userPreference.setTid(815); 
            }
            else
            {
                userPreference.setTid(830);                     
            }

            Log.d(TAG, "Inserting Tid and Dage");
            mapper.save(userPreference);
            Log.d(TAG, "Tid and Dage inserted");
        }
    } catch (AmazonServiceException ex) {
        Log.e(TAG, "Error inserting users");
        UserPreferenceDemoActivity.clientManager
                .wipeCredentialsOnAuthError(ex);
    }
} 

但是 AWS DynamoDB 服务中的顺序是:

如何按升序对表格进行排序，以便获得如下顺序:800,815,830

Answer 1

哈希在 DynamoDB 中没有排序。此处唯一的解决方法是扫描整个表以在应用程序层中进行编码和排序。