Method isRefTrivial

core/src/main/java/org/apache/calcite/rel/RelRoot.java:234–243

Returns true if the embedded relation is either a DML relation or if the field order defined in this RelRoot is the same as the field order of the embedded relation, otherwise false. Positive example (same order): RelRoot: { rel: Project(name, empno) TableScan(EMP)

()

   *   are in the same order as in the embedded relation, otherwise false
   */
  public boolean isRefTrivial() {
    if (SqlKind.DML.contains(kind)) {
      // DML statements return a single count column.
      // The validated type is of the SELECT.
      // Still, we regard the mapping as trivial.
      return true;
    }
    final RelDataType inputRowType = rel.getRowType();
    return Mappings.isIdentity(fields.leftList(), inputRowType.getFieldCount());
  }

  /**
   * Returns true if the embedded relation has a single collation defined which matches the