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  1. IMPALA
  2. IMPALA-3680

Reset the file offset after failed cache reads

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: Impala 2.6.0
    • Fix Version/s: Impala 2.7.0, Impala 2.6.2
    • Component/s: Backend
    • Labels:
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      Description

      Currently we don't reset the file read offset if ZCR fails. Due to this, when we switch to the normal read path, we hit the eosr of the scan-range even before reading the expected data length. This results in re-issuing the whole set of scan ranges and hence a severe
      performance hit.

      This has been observed while debugging IMPALA-3679, where zero-copy reads don't work with encryption zones. However this situation can apply to any general case where the ZCRs fail.

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            • Assignee:
              bharathv bharath v
              Reporter:
              bharathv bharath v
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              Dates

              • Created:
                Updated:
                Resolved: