英文:
dynamodb query with filters returns no items
问题
| id(string) | message(string) | created(number) | completed(boolean) |
|---|---|---|---|
| 123 | 指示 | 1686731293161 | - |
| ... | ... | ... | ... |
| 129 | 指示 | 1686821275413 | false |
分区键: 消息<br />
排序键: 创建时间<br />
投影键: 所有<br />
对于表格的总结：
- 有些条目没有消息和已完成属性
- 即使消息在 GSI 中用作分区键，对于我的用例来说没问题
我尝试使用 aws-sdk dynamodb 客户端查询，参数如下：
TableName: "test-idStatus",IndexName: "messageCreatedIndex",KeyConditionExpression: "#message = :message and #created BETWEEN :createdfrom AND :createdto",ExpressionAttributeNames: {"#message": "message","#created": "created","#completed": "completed",},ExpressionAttributeValues: {":messageFunction": "Instruction",":createdfrom": 1686817506000, // 2023 年 6 月 15 日 08:25":createdto": 1686821106000, // 2023 年 6 月 15 日 09:25":completed": "false",},ScanIndexForward: false,Limit: 5,Select: "ALL_ATTRIBUTES",FilterExpression: "#completed = :completed",}``` 这返回了条目。但是当我将 `ExpressionAttributeValues` 中的以下值更改为：<br/>`createdfrom`: 1686731286000 (2023 年 6 月 14 日 08:25) <br/>这没有返回任何条目（但返回了 LastEvaluatedKey）。<br/>这很奇怪，因为 6 月 15 日返回了条目，只是 6 月 14 日到 6 月 15 日的条目的子集。我还尝试在 AWS 控制台 DynamoDB 中复制这个问题，结果相同。然后我还尝试移除 `ScanIndexForward`，现在返回了条目。<details><summary>英文:</summary>|id(string)|message(string)|created(number)|completed(boolean)||-|-|-|-||123|Instruction|1686731293161|-||...|...| ...|...||129|Instruction|1686821275413|false|`Partition key`: message<br />`Sort key`: created<br />`Projected keys`: All<br />In summary for the table:- some entries does not have message and completed attributes- even though message is used as partition key in GSI, this is ok for my use caseI tried to query using aws-sdk dynamodb client with this params:```{TableName: "test-idStatus",IndexName: "messageCreatedIndex",KeyConditionExpression: "#message = :message and #created BETWEEN :createdfrom AND :createdto",ExpressionAttributeNames: {"#message": "message","#created": "created","#completed": "completed",},ExpressionAttributeValues: {":messageFunction": "Instruction",":createdfrom": 1686817506000, // 2023-June-15 08:25":createdto": 1686821106000, // 2023-June-15 09:25":completed": "false",},ScanIndexForward: false,Limit: 5,Select: "ALL_ATTRIBUTES",FilterExpression: "#completed = :completed",}
This returned entries
But when I changed the ExpressionAttributeValues of:<br/>
createdfrom: 1686731286000 (2023-June-14 08:25) <br/>
This did not return any entries (but returns a LastEvaluatedKey).<br/>
Which is weird since June-15 returned entries which is just a subset of June-14 to June-15 entries
I also tried to replicate this in the AWS console dynamoDB,
The same thing happened.
Then I also tried removing ScanIndexForward, now it returned entries.
答案1
得分: 2
发生的情况是你设置了一个FilterExpression和一个Limit。现在发生的是DynamoDB读取了5个项目，因为这是你的Limit，然后将你的过滤器应用于这5个项目，但没有一个匹配表达式，所以你得到了一个空响应。
更改日期只是简单地改变了读取的5个项目，很幸运它们匹配了你的过滤器。更改扫描方向也是一样的，你只是改变了前5个项目。
英文:
What's happening here is that you set a FilterExpression and a Limit. What happens now is that DynamoDB reads 5 items as that is your Limit and then applies your filter to those 5 items but none match the expression so you get an empty response.
Changing the date is simply changing the 5 items read and it's just luck that they match your filter. The same goes for changing the scan direction, you're just changing the first 5 items.
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