CancelMPPQuery should cancel the on flight coprocessor read for the related mpp query
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- Dominant language
- C++
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Description
Enhancement
Currently, TiFlash support CancelMPPQuery, which will cancel a mpp query with specific start_ts, however, it only cancel the mpp task, and will ignore the coprocessor tasks which were triggered by the mpp task due to RemoteRead, this does not make sense since the on flight coprocessor read is meaningless after related mpp query was cancelled, so CancelMPPQuery should also cancel the on flight coprocessor read for the related mpp query.
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First steps
- Read the whole issue, then the project's contributing guide.
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- Open a pull request that references the issue number.
Research direction
Start in dbms/src/Flash/Coprocessor/DAGQueryBlockInterpreter.cpp at the referenced RemoteRead call, then trace how CancelMPPQuery identifies and cancels the MPP task for a start_ts. Determine where related in-flight coprocessor reads are tracked and how cancellation is propagated. Done means cancelling an MPP query also cancels its triggered coprocessor reads.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- distributed-systems
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100