Question

我正在尝试在DynamoDB中创建一个表并发布该表，列出所有现有表。我使用的代码是

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using Amazon;
using Amazon.DynamoDBv2;
using Amazon.DynamoDBv2.Model;
using Amazon.Runtime;

namespace DynamoDBTester
{
class Program
{
    private static AmazonDynamoDBClient client = new AmazonDynamoDBClient();
    private static string tableName = "DummyTable";
    static void Main(string[] args)
    {
       // try
        //{
            CreateDummyTable();
           // ListMyTables();

            Console.WriteLine("To continue, press Enter");
            Console.ReadLine();
        //}
        //catch (AmazonDynamoDBException e) { Console.WriteLine(e.Message); }
        //catch (AmazonServiceException e) { Console.WriteLine(e.Message); }
        //catch (Exception e) { Console.WriteLine(e.Message); }
    }

    private static void CreateDummyTable()
    {
        Console.WriteLine("\n*** Creating DummyTable ***");
        var request = new CreateTableRequest
        {
            AttributeDefinitions = new List<AttributeDefinition>()
        {
            new AttributeDefinition
            {
                AttributeName = "Id",
                AttributeType = "N"
            }
            ,
            new AttributeDefinition
            {
                AttributeName = "DateTime",
                AttributeType = "S"
            }
            ,
            new AttributeDefinition
            {
                AttributeName = "Temperature",
                AttributeType = "N"
            }
        },
            KeySchema = new List<KeySchemaElement>
            {
                new KeySchemaElement
            {
                AttributeName = "Id",
                KeyType = "HASH" //Partition key
            },
                new KeySchemaElement
            {
                AttributeName = "DateTime",
                KeyType = "RANGE" //Partition key
            },
                new KeySchemaElement
            {
                AttributeName = "Temperature",
                KeyType = "RANGE" //Partition key
            }

        },
            ProvisionedThroughput = new ProvisionedThroughput
            {
                ReadCapacityUnits = 5,
                WriteCapacityUnits = 6
            },
            TableName = tableName
        };
        var response = client.CreateTable(request);
        var tableDescription = response.TableDescription;
        Console.WriteLine("{1}: {0} \t ReadsPerSec: {2} \t WritesPerSec: {3}",
                  tableDescription.TableStatus,
                  tableDescription.TableName,
                  tableDescription.ProvisionedThroughput.ReadCapacityUnits,
                  tableDescription.ProvisionedThroughput.WriteCapacityUnits);

        string status = tableDescription.TableStatus;
        Console.WriteLine(tableName + " - " + status);

        WaitUntilTableReady(tableName);
    }
    private static void WaitUntilTableReady(string tableName)
    {
        string status = null;
        // Let us wait until table is created. Call DescribeTable.
        do
        {
            System.Threading.Thread.Sleep(5000); // Wait 5 seconds.
            try
            {
                var res = client.DescribeTable(new DescribeTableRequest
                {
                    TableName = tableName
                });

                Console.WriteLine("Table name: {0}, status: {1}",
                          res.Table.TableName,
                          res.Table.TableStatus);
                status = res.Table.TableStatus;
            }
            catch (ResourceNotFoundException)
            {
                // DescribeTable is eventually consistent. So you might
                // get resource not found. So we handle the potential exception.
            }
        } while (status != "ACTIVE");
    }
    private static void ListMyTables()
    {
        Console.WriteLine("\n*** listing tables ***");
        string lastTableNameEvaluated = null;
        do
        {
            var request = new ListTablesRequest
            {
                Limit = 2,
                ExclusiveStartTableName = lastTableNameEvaluated
            };

            var response = client.ListTables(request);
            foreach (string name in response.TableNames)
                Console.WriteLine(name);

            lastTableNameEvaluated = response.LastEvaluatedTableName;
        } while (lastTableNameEvaluated != null);
    }



}
}

但是我得到了错误

Additional information: 1 validation error detected: Value '[com.amazonaws.dynamodb.v20120810.KeySchemaElement@21c24a, com.amazonaws.dynamodb.v20120810.KeySchemaElement@7357d4d9, com.amazonaws.dynamodb.v20120810.KeySchemaElement@7b38ae72]' at 'keySchema' failed to satisfy constraint: Member must have length less than or equal to 2

我的表名是DummyTable

它应该有3列：

1.Id

2.DateTime

3.温度

其中Id是PrimaryKey

Answer 1

<强>问题： -

1）只能将一个属性定义为RANGE键。您有两个属性DateTime和Temperature定义为RANGE键

<强>解决方案： -

如果您需要两个不同的RANGE键，则可以使用本地二级索引（LSI）。一张表可以有5个LSI。

LSI

Answer 2

创建表时，您只需指定该表的主键（KeySchema）

a.simple主键（仅分区键）或

b.complex主键（分区+排序键）

在您的情况下，它的复杂主键只需要提及分区键和排序键（只有发电机数据库所需的模式）

无需提及附加属性（创建表时附加列名称）。

需要更改代码是删除添加属性定义和架构

var request = new CreateTableRequest
        {
            AttributeDefinitions = new List<AttributeDefinition>()
        {
            new AttributeDefinition
            {
                AttributeName = "Id",
                AttributeType = "N"
            }
            ,
            new AttributeDefinition
            {
                AttributeName = "DateTime",
                AttributeType = "S"
            }
}

KeySchema = new List<KeySchemaElement>
            {
                new KeySchemaElement
            {
                AttributeName = "Id",
                KeyType = "HASH" //Partition key
            },
                new KeySchemaElement
            {
                AttributeName = "DateTime",
                KeyType = "RANGE" //Range key
            }
}

Answer 3

在创建表时，您只需要保留具有哈希或范围架构属性的列即可。

对于创建表时无需提及的其他列。在插入项目时，您可以动态地将任意数量的列添加到记录中，并将其保存在指定的hash / range属性中。

c＃在Dynamo DB中创建表

3 个答案: