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  1. IMPALA
  2. IMPALA-1382

Wasted space in buffered-tuple-stream in presence of many NULL tuples

    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: Impala 2.0
    • Fix Version/s: Impala 2.10.0
    • Component/s: Backend
    • Labels:
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      Description

      We currently preallocate the null tuple indicator bitstring in each tuple stream assuming that very few tuples will be NULL. That can lead to lots of wasted space in the buffer if there are many NULL tuples in the stream.

      A possible solution is to use a slotted page (buffer) with NULL indicators growing from the end of the page (buffer).

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              • Assignee:
                tarmstrong Tim Armstrong
                Reporter:
                ippokratis Ippokratis Pandis
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                • Created:
                  Updated:
                  Resolved: