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  1. Kudu
  2. KUDU-2854

Short circuit predicates on dictionary-coded columns

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    Details

    • Type: Improvement
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: cfile, perf, tserver
    • Labels:
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      Description

      In the common case that a column has no updates in a given DRS, if we see that no entries in the dictionary match the predicate, we can short circuit at a few layers:

      • we can store a flag in the cfile footer that indicates that all blocks are dict-coded (ie there are no fallbacks). In that case, we can skip the whole rowset
      • if a cfile is partially dict-encoded, we can skip any dict-coded blocks without decoding the dictionary words

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            • Assignee:
              helifu LiFu He
              Reporter:
              tlipcon Todd Lipcon
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              • Created:
                Updated: