为什么 DynamoDB 查询中没有**不等于**比较? [英] Why is there no **not equal** comparison in DynamoDB queries?

问题描述

我尝试使用生成分区键 category 和排序键 tinponId 的二级索引查询我的表 Tinpon.我的目标是排除具有某些 tinponIds 的项目.我的第一个想法是进行否定比较:<代码>keyConditionExpression = "类别 = :category AND tinponId != :tinponId"但只有相等的 = 比较.然后我尝试了其他方法(遗憾的是不存在):<代码>keyConditionExpression = "类别 = :category NOT tinponId = :tinponId"keyConditionExpression = "category = :category AND tinponId <> :tinponId"keyConditionExpression = "类别 = :category AND tinponId < :tinponId AND tinponId > :tinponId"遵循 AWS 指南没有不等于比较.为什么这样?有没有办法查询 DynamoDB，不包括 id 列表，或者是检索一大堆项目并稍后手动过滤它们的唯一选择?

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 不允许排序键不等于.但是，您可以在 FilterExpression 中使用 "Not Equals i.e. <>".

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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