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  1. Calcite
  2. CALCITE-4241

Some improvements to metadata query

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    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 1.26.0
    • Component/s: core

      Description

      1. For {{RelMdColumnUniqueness#areColumnsUnique(RelSubset, RelMetadataQuery,
        ImmutableBitSet, boolean)}}, we can return early as we encounter the first null.
      2. For {{RelMdDistinctRowCount#getDistinctRowCount(Values, RelMetadataQuery,
        ImmutableBitSet, RexNode)}}, we can get the distinct row count accurately, instead of guessing that half of the elements are distinct. 
      3. RelMdUtil#areColumnsDefinitelyUniqueWhenNullsFiltered could be implemented in a more efficient way. 

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              • Assignee:
                fan_li_ya Liya Fan
                Reporter:
                fan_li_ya Liya Fan
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