[IOTDB-514] To support aggregation in the distributed version - ASF JIRA

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Details

Type: Improvement
Status: Closed
Priority: Major
Resolution: Fixed
Affects Version/s: None
Fix Version/s: 0.10.0, master branch
Component/s: None
Labels:

Description

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.