如何检查电子邮件和用户名在dynamodb表设计中是否唯一答案

【问题标题】：how to check if email and username is unique in dynamodb table design如何检查电子邮件和用户名在dynamodb表设计中是否唯一
【发布时间】：2022-01-21 01:31:39
【问题描述】：

我正在创建一个潜在客户表，其中每个潜在客户都有一个 id (uuid)，它是 patrtision 键和 createdAt rangekey。每次将新项目插入潜在客户表时，我都需要执行重复检查

关于运行以下命令

C:\Users\user>aws dynamodb describe-table --table-name serverless-isd-app-leads-dev --endpoint-url http://localhost:8008

这是显示的结果

{
    "Table": {
        "AttributeDefinitions": [
            {
                "AttributeName": "id",
                "AttributeType": "S"
            },
            {
                "AttributeName": "email",
                "AttributeType": "S"
            },
            {
                "AttributeName": "phone",
                "AttributeType": "S"
            },
            {
                "AttributeName": "createdAt",
                "AttributeType": "N"
            }
        ],
        "TableName": "serverless-isd-app-leads-dev",
        "KeySchema": [
            {
                "AttributeName": "id",
                "KeyType": "HASH"
            },
            {
                "AttributeName": "createdAt",
                "KeyType": "RANGE"
            }
        ],
        "TableStatus": "ACTIVE",
        "CreationDateTime": "2021-12-18T20:54:11.940000+05:30",
        "ProvisionedThroughput": {
            "LastIncreaseDateTime": "1970-01-01T05:30:00+05:30",
            "LastDecreaseDateTime": "1970-01-01T05:30:00+05:30",
            "NumberOfDecreasesToday": 0,
            "ReadCapacityUnits": 1,
            "WriteCapacityUnits": 1
        },
        "TableSizeBytes": 0,
        "ItemCount": 0,
        "TableArn": "arn:aws:dynamodb:ddblocal:000000000000:table/serverless-isd-app-leads-dev",
        "GlobalSecondaryIndexes": [
            {
                "IndexName": "emai_phone_index",
                "KeySchema": [
                    {
                        "AttributeName": "email",
                        "KeyType": "HASH"
                    },
                    {
                        "AttributeName": "phone",
                        "KeyType": "RANGE"
                    }
                ],
                "Projection": {
                    "ProjectionType": "ALL"
                },
                "IndexStatus": "ACTIVE",
                "ProvisionedThroughput": {
                    "ReadCapacityUnits": 1,
                    "WriteCapacityUnits": 1
                },
                "IndexSizeBytes": 0,
                "ItemCount": 0,
                "IndexArn": "arn:aws:dynamodb:ddblocal:000000000000:table/serverless-isd-app-leads-dev/index/emai_phone_index"
            }
        ]
    }
}

这是我的查询参数

const params = {
        TableName: process.env.LEADS_TABLE,
        IndexName: "emai_phone_index",
        Item: {
          id: data.id,
          email: data.email,
          phone: data.phone,
          firstName: data.firstName,
          lastName: data.lastName,
          createdAt: data.createdAt,
          updatedAt: data.updatedAt,
        },
        ConditionExpression:
          "attribute_not_exists(#email) AND attribute_not_exists(#phone)",
        ExpressionAttributeNames: {
          "#email": "email",
          "#phone": "phone",
        },
      };

但由于电子邮件和电话在全球二级索引上，我无法找到它是否重复。

我该如何解决这个问题？或者有没有其他方法来设计一个更好的表

【问题讨论】：

标签： nosql amazon-dynamodb dynamodb-queries

【解决方案1】：

不用创建全局二级索引，你可以通过在写新记录的时候额外增加“email”和“phone”两项来实现唯一性。对于这两条记录，您的主键将设置为由井号分隔的那些属性值（电子邮件和电话）。所以写一共会涉及三条记录，删除的时候也要把这三条记录删掉。

类似的东西：

'[
  {
    "Put": {
      "TableName" : "serverless-isd-app-leads-dev", 
      "ConditionExpression": "attribute_not_exists(id)",
        "Item" : {
          "id":{"S":"b201c1f2-238e-461f-88e6-0e606fbc3c51"},
          "email":{"S":"bobby.tables@gmail.com"},
          "firstName":{"S":"Bobby"},
          "lastName":{"S":"Tables"},
          "phone":{"S":"+1-202-555-0124"}
       }
    }
},
  {
    "Put": {
      "TableName" : "serverless-isd-app-leads-dev", 
      "ConditionExpression": "attribute_not_exists(id)",
      "Item" : {
        "id":{"S":"phone#+1-202-555-0124"}
       }
    }
},
  {
    "Put": {
      "TableName" : "serverless-isd-app-leads-dev", 
      "ConditionExpression": "attribute_not_exists(id)",
      "Item" : {
        "id":{"S":"email#bobby.tables@gmail.com"}
       }
    }
}
]'

请阅读以下链接以了解具有类似用例的详细信息： Simulating Amazon DynamoDB unique constraints using transactions

【讨论】：