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https://issues.apache.org/jira/browse/CALCITE-4241?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Liya Fan updated CALCITE-4241:
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Description:
# For {{RelMdColumnUniqueness#areColumnsUnique(RelSubset, RelMetadataQuery,
ImmutableBitSet, boolean)}}, we can return early as we encounter the first
null.
# 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.
# {{RelMdUtil}}#{{areColumnsDefinitelyUniqueWhenNullsFiltered}} could be
implemented in a more efficient way.
was:
# For {{RelMdColumnUniqueness#areColumnsUnique(RelSubset, RelMetadataQuery,
ImmutableBitSet, boolean)}}, we can return early as we encounter the first
null.
# 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.
# In class {{RelMdUtil}}, {{areColumnsDefinitelyUnique}} and
{{areColumnsDefinitelyUniqueWhenNullsFiltered}} have identical behaviors, so we
should use the formmer, which is more efficient.
> Some improvements to metadata query
> -----------------------------------
>
> Key: CALCITE-4241
> URL: https://issues.apache.org/jira/browse/CALCITE-4241
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Liya Fan
> Assignee: Liya Fan
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> # For {{RelMdColumnUniqueness#areColumnsUnique(RelSubset, RelMetadataQuery,
> ImmutableBitSet, boolean)}}, we can return early as we encounter the first
> null.
> # 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.
> # {{RelMdUtil}}#{{areColumnsDefinitelyUniqueWhenNullsFiltered}} could be
> implemented in a more efficient way.
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