为什么使用更新表达式更新 DynamoDB 项目会导致 500 InternalFailure 和 30 秒挂起？

Question

我在尝试使用 Node.js AWS SDK (AWS.DynamoDB.DocumentClient) 使用 UpdateExpression 执行更新时收到 500 Internal Error。

操作挂起大约 30 秒，然后 returns 此错误：

InternalFailure: null
    at Request.extractError (WORKSPACE/node_modules/aws-sdk/lib/protocol/json.js:52:27)
    at Request.callListeners (WORKSPACE/node_modules/aws-sdk/lib/sequential_executor.js:106:20)
    at Request.emit (WORKSPACE/node_modules/aws-sdk/lib/sequential_executor.js:78:10)
    at Request.emit (WORKSPACE/node_modules/aws-sdk/lib/request.js:688:14)
    at Request.transition (WORKSPACE/node_modules/aws-sdk/lib/request.js:22:10)
    at AcceptorStateMachine.runTo (WORKSPACE/node_modules/aws-sdk/lib/state_machine.js:14:12)
    at WORKSPACE/node_modules/aws-sdk/lib/state_machine.js:26:10
    at Request.<anonymous> (WORKSPACE/node_modules/aws-sdk/lib/request.js:38:9)
    at Request.<anonymous> (WORKSPACE/node_modules/aws-sdk/lib/request.js:690:12)
    at Request.callListeners (WORKSPACE/node_modules/aws-sdk/lib/sequential_executor.js:116:18) {
  code: 'InternalFailure',
  time: 2021-10-08T16:24:49.756Z,
  requestId: 'EJJH7IIRFCS0HOPNQ9IIS39CKJVV4KQNSO5AEMVJF66Q9ASUAAJG',
  statusCode: 500,
  retryable: true
}

我在运行我在 Lambda 函数中的代码以及运行在本地使用 DynamoDB REST API 时都得到了这个（所以这不是 Lambda 权限问题）。

导致此内部错误的原因是什么？

我更新项目的代码：

export async function addOverride(addOverrideRequest: any) {
    const addListIfNotExists = {
        TableName: addOverrideRequest.table,
        Key: {
            Environment: addOverrideRequest.environment
        },
        UpdateExpression: "SET Overrides.:overrideAttr = :emptylist",
        ConditionExpression: "attribute_not_exists(Overrides.:overrideAttr)",
        ExpressionAttributeValues: {
            ":overrideAttr": addOverrideRequest.overrideField,
            ":emptylist": [],
          },
    }

    try {
        const result = await DOCUMENT_CLIENT.update(addListIfNotExists).promise();
    } catch (error) {
        throw error;
    }
}

请求解析为：

{
  TableName: 'AppVersions',
  Key: { Environment: 'int' },
  UpdateExpression: 'SET Overrides.:overrideAttr = :emptylist',
  ConditionExpression: 'attribute_not_exists(Overrides.:overrideAttr)',
  ExpressionAttributeValues: { ':overrideAttr': 'EyeTrackerType', ':emptylist': [] }
}

Answer 1

使用 ExpressionAttributeNames 定义您的属性名称，而不是将它们添加到 ExpressionAttributeValues。

ExpressionAttributeNames 用于指定动态属性名称，但是，您在 [=24] 中指定 overrideAttr =]表达式属性值.

此外，您必须使用井号 - # - 来指示属性名称的占位符。

这应该有效：

const addListIfNotExists = {
    TableName: addOverrideRequest.table,
    Key: {
        Environment: addOverrideRequest.environment
    },
    UpdateExpression: "SET Overrides.#overrideAttr = :emptylist",
    ConditionExpression: "attribute_not_exists(Overrides.#overrideAttr)",
    ExpressionAttributeNames: {
        "#overrideAttr": addOverrideRequest.overrideField
    },
    ExpressionAttributeValues: {
        ":emptylist": []
    },
}

为什么使用更新表达式更新 DynamoDB 项目会导致 500 InternalFailure 和 30 秒挂起？

Why does a DynamoDB item update with an update expression cause a 500 InternalFailure & a 30 second hang?

amazon-web-services

node.js

amazon-dynamodb