[jira] [Created] (CALCITE-4203) RelMdUniqueKeys should not return empty when meeting Intersect and Minus if its input has unique keys

[Chunwei Lei (Jira)]

Chunwei Lei created CALCITE-4203:
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             Summary: RelMdUniqueKeys should not return empty when meeting 
Intersect and Minus if its input has unique keys
                 Key: CALCITE-4203
                 URL: https://issues.apache.org/jira/browse/CALCITE-4203
             Project: Calcite
          Issue Type: Improvement
            Reporter: Chunwei Lei
            Assignee: Chunwei Lei


Currently, we get an empty unique key for Intersect and Minus if its all is 
true. 

 
{code:java}
// code placeholder
public Set<ImmutableBitSet> getUniqueKeys(SetOp rel, RelMetadataQuery mq,
    boolean ignoreNulls) {
  if (!rel.all) {
    return ImmutableSet.of(
        ImmutableBitSet.range(rel.getRowType().getFieldCount()));
  }
  return ImmutableSet.of();
}
{code}
However, from the semantic of Intersect and Minus, we can get their unique keys 
from its input even if its all is true. 



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