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https://issues.apache.org/jira/browse/IOTDB-514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17043464#comment-17043464
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Yuxin Zhang commented on IOTDB-514:
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hi, I'm fixing this issue.
> To support aggregation in the distributed version
> -------------------------------------------------
>
> Key: IOTDB-514
> URL: https://issues.apache.org/jira/browse/IOTDB-514
> Project: Apache IoTDB
> Issue Type: Improvement
> Reporter: Tian Jiang
> Priority: Major
> Labels: aggregation, distributed, query
> Fix For: master branch
>
>
> The current aggregation cannot satisfy the needs in the distributed version,
> to be specific, there are two points that should be satisfied:
> 1. The FirstValueAggrResult and LastValueAggrResult should also contain
> timestamp.
> Without a timestamp, the coordinator node cannot tell the result from which
> node is the true first/last.
> 2. An AggrResult should be able to merge with another. When we get
> AggrResults from all nodes that participate in the query, these results
> should be merged to generate a new result.
> To resolve the issue, you should:
> 1. Add a field `timestamp` in FirstValueAggrResult and LastValueAggrResult
> 2. Add an abstract method `merge(AggregateResult another)` in AggregateResult
> and implement it properly.
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