为什么DynamoDB查询中没有“不相等”比较？ [英] Why is there no **not equal** comparison in DynamoDB queries?

问题描述

我尝试用辅助索引查询表 Tinpon ，该索引产生分区键类别和排序键 tinponId 。我的目标是排除具有某些tinponIds的项目。我首先想到的是做一个负比较：

keyConditionExpression = category =：category AND tinponId！=：tinponId

，但只有相等的 = 比较。然后我尝试了其他的服务方法（可悲的是不存在）：

keyConditionExpression = category =：category NOT tinponId =：tinponId
keyConditionExpression = category = ：category AND tinponId<>：tinponId
keyConditionExpression = category =：category AND tinponId<：tinponId AND tinponId>：tinponId

在 AWS指南之后，没有不相等比较。为什么这样？
还有什么方法可以查询DynamoDB，但不包括ID列表，还是唯一的选项来检索一整堆项目并稍后手动对其进行过滤？

I try to query my table Tinpon with a secondary index yielding a partition-key category and sort-key tinponId. My goal is to exclude items with certain tinponIds. My first thought would be to make a negative compare: keyConditionExpression = "category = :category AND tinponId != :tinponId" but there is only a equal = comparison. Then I tried serval other methods (with sadly do not exist): keyConditionExpression = "category = :category NOT tinponId = :tinponId" keyConditionExpression = "category = :category AND tinponId <> :tinponId" keyConditionExpression = "category = :category AND tinponId < :tinponId AND tinponId > :tinponId" Following the AWS guide there is no not equal comparisson. Why so? And is there a way to query DynamoDB excluding a list of ids or is the only option to retrieve a whole bunch of items and filter them later manually?

推荐答案

KeyConditionExpression 不允许对排序键使用不等于。但是，您可以在 FilterExpression 中使用不等于，即<> 。

The KeyConditionExpression doesn't allow not equals for the sort key. However, you can use the "Not Equals i.e. <>" in FilterExpression.

KeyConditionExpression : 'category = :category',    
FilterExpression : 'tinponId  <> :tinponIdVal',
ExpressionAttributeValues : {
    ':category' : 'somevalue',
    ':tinponIdVal' :  'somevalue'
}

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