[jira] [Created] (CALCITE-1498) RelMdUtil.checkInputForCollationAndLimit() should also consider input collations as a zero-length collation list.

["Maryann Xue (JIRA)" <ji...@apache.org>]

Maryann Xue created CALCITE-1498:
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             Summary: RelMdUtil.checkInputForCollationAndLimit() should also consider input collations as a zero-length collation list.
                 Key: CALCITE-1498
                 URL: https://issues.apache.org/jira/browse/CALCITE-1498
             Project: Calcite
          Issue Type: Bug
          Components: core
    Affects Versions: 1.10.0
            Reporter: Maryann Xue
            Assignee: Maryann Xue
            Priority: Minor


{code}
    // Check if the input is already sorted
    boolean alreadySorted = false;
    if (!alreadySorted) {
      for (RelCollation inputCollation : mq.collations(input)) {
        if (inputCollation.satisfies(collation)) {
          alreadySorted = true;
          break;
        }
      }
    }
{code}
if {{mq.collations(input)}} returns an empty array, {{alreadySorted}} will always be false even if the required {{collation}} is an empty collation (which indicates there's no need to sort).



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