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

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.26.0
• Labels: pull-request-available
• Assignee: Chunwei Lei
• Reporter: Chunwei Lei
• Created: 01/Sep/20 03:17
• Updated: 06/Oct/20 17:17
• Resolved: 03/Sep/20 06:27

Description

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

 

// 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();
}

However, from the semantic of Intersect and Minus, we can get their unique keys from its input even if its all is true. 

Issue Links

• links to: GitHub Pull Request #2126