docs: @Override
      public boolean isOrderDeterministic() {
          if ( ! hasTopLevelScans()) {
              // This currently applies to parent queries that do all their
              // scanning in subqueries and so take on the order determinism of
              // their subqueries. This might have to be rethought to allow
              // ordering in parent queries to effect determinism of unordered
              // "FROM CLAUSE" subquery results.
              return true;
          }
  
          if (hasAOneRowResult()) {
              return true;
          }
  
          if ( ! hasOrderByColumns() ) {
              return false;
          }
  
          // The nonOrdered expression list is used as a short-cut
          // -- if an expression has been determined to be
          // non-ordered when encountered as a GROUP BY expression,
          // it will also be non-ordered when encountered in the select list.
          ArrayList<AbstractExpression> nonOrdered = new ArrayList<>();
  
          if (isGrouped()) {
              // Does the ordering of a statements's GROUP BY columns
              // ensure determinism?
              // All display columns and order-by expressions
              // are functionally dependent on the GROUP BY
              // columns even if the display column's values
              // are not ordered or unique,
              // so ordering by ALL of the GROUP BY columns is enough
              // to get full determinism,
              // EVEN if ordering by other (dependent) expressions,
              // regardless of the placement of non-GROUP BY expressions
              // in the ORDER BY list.
              if (orderByColumnsDetermineAllColumns(m_groupByColumns, nonOrdered)) {
                  return true;
              }
  
              if (orderByColumnsDetermineAllDisplayColumns(nonOrdered)) {
                  return true;
              }
  
          }
          else {
              if (orderByColumnsDetermineAllDisplayColumns(nonOrdered)) {
                  return true;
              }
  
              if (orderByColumnsCoverUniqueKeys()) {
                  return true;
              }
          }
          return false;
      }