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  1. IMPALA
  2. IMPALA-4580

Crash when FETCH_FIRST exhausts result set cache

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Blocker
    • Resolution: Fixed
    • Affects Version/s: Impala 2.8.0
    • Fix Version/s: Impala 2.8.0
    • Component/s: Backend
    • Labels:
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      Description

      The following sequence can lead to a crash:

      1. Client sets result cache size to N
      2. Client issues query with #results < N
      3. Client fetches all results, triggering eos and tearing down Coordinator::root_sink_.
      4. Client restarts query with FETCH_FIRST.
      5. Client reads all results again. After cache is exhausted, Coordinator::GetNext() is called to detect eos condition again.
      6. GetNext() hits DCHECK(root_sink_ != nullptr).

      Either the QES or the coordinator need to remember that eos was once true, and turn GetNext() into a no-op if so.

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            • Assignee:
              henryr Henry Robinson
              Reporter:
              henryr Henry Robinson
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              • Created:
                Updated:
                Resolved: