private boolean isLateralView(RelNode relNode) {
    if (!(relNode instanceof TableFunctionScan)) {
      return false;
    }
    TableFunctionScan htfs = (TableFunctionScan) relNode;
    RexCall call = (RexCall) htfs.getCall();
    return ((RexCall) htfs.getCall()).getOperator() == SqlStdOperatorTable.LATERAL;
  }
Add PK-FK join information to the AST as a query hint
@param ast
@param join
@param swapSides whether the left and right input of the join is swapped
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/translator/ASTConverter.java