Question

我的DynamoDB架构是：

TableName = 'Cities'
PrimaryIndex = '_id'
SecondaryIndex = 'areaId-timestamp-index'
  - areaId is primary key
  - timestamp is sort key

DynamoDB中的数据结构如下所示：

{ _id: '....', name: 'New York', areaId: 22, timestamp: 1478882557071 },
{ _id: '....', name: 'Washington', areaId: 22, timestamp: 1478882557071 },
{ _id: '....', name: 'Copenhagen', areaId: 18, timestamp: 1478882557071 },
{ _id: '....', name: 'Berlin', areaId: 12, timestamp: 1478882557071 },

我希望能够在以下条件下对城市进行分页：

只有来自，fx，id为22的区域的城市
必须根据时间戳

我的查询如下：

const areaId = 22

const params = {
  TableName: 'Cities',
  Limit: 10,
  IndexName: 'areaId-timestamp-index',
  KeyConditionExpression: 'areaId = :x',
  ExpressionAttributeValues: {
    ':x': areaId
  }
}

dynamo.query(params)

当我运行此操作时，我会收到lastEvaluatedKey

LastEvaluatedKey = {
    areaId: 22,
    _id: '8c43-d917-f9ec',  // ID of last item in batch
    timestamp: 1478882561962  // Timestamp of last item in batch 
}

当我然后运行下一个后续查询（以获得更多结果）时，我添加ExclusiveStartKey属性，其值与LastEvaluatedKey中返回的值完全相同。

但是，当我运行查询时，我得到：

The provided key element does not match the schema

Answer 1

尝试将LastEvaluatedKey提供给ExclusiveStartKey，您必须以任何格式提供您收到的整个价值。

const areaId = 22
const params = {
  TableName: 'Cities',
  Limit: 10,
  LastEvaluatedKey:response.ExclusiveStartKey, // Get it from previous query respose and use in same format
  IndexName: 'areaId-timestamp-index',
  KeyConditionExpression: 'areaId = :x',
  ExpressionAttributeValues: {
    ':x': areaId
  }
}

希望这有帮助，感谢

DynamoDB中的分页与全球二级指数

1 个答案: