Method init

fe/src/main/java/org/apache/impala/planner/UnionNode.java:312–351

Must be called after addChild()/addConstExprList(). Computes the materialized result/const expr lists based on the materialized slots of this UnionNode's produced tuple. The UnionNode doesn't need an smap: like a ScanNode, it materializes an original tuple. There is no need to call assignConjuncts()

(Analyzer analyzer)

   * been evaluated during registration to set analyzer.hasEmptyResultSet_.
   */
  @Override
  public void init(Analyzer analyzer) {
    Preconditions.checkState(conjuncts_.isEmpty());
    computeMemLayout(analyzer);
    computeStats(analyzer);
    computePassthrough(analyzer);

    // drop resultExprs/constExprs that aren't getting materialized (= where the
    // corresponding output slot isn't being materialized)
    materializedResultExprLists_.clear();
    Preconditions.checkState(resultExprLists_.size() == children_.size());
    List<SlotDescriptor> slots = analyzer.getDescTbl().getTupleDesc(tupleId_).getSlots();
    for (int i = 0; i < resultExprLists_.size(); ++i) {
      List<Expr> exprList = resultExprLists_.get(i);
      List<Expr> newExprList = new ArrayList<>();
      Preconditions.checkState(exprList.size() == slots.size());
      for (int j = 0; j < exprList.size(); ++j) {
        if (slots.get(j).isMaterialized()) newExprList.add(exprList.get(j));
      }
      materializedResultExprLists_.add(
          Expr.substituteList(newExprList, getChild(i).getOutputSmap(), analyzer, true));
    }
    Preconditions.checkState(
        materializedResultExprLists_.size() == getChildren().size());

    materializedConstExprLists_.clear();
    for (List<Expr> exprList: constExprLists_) {
      Preconditions.checkState(exprList.size() == slots.size());
      List<Expr> newExprList = new ArrayList<>();
      for (int i = 0; i < exprList.size(); ++i) {
        if (slots.get(i).isMaterialized()) {
          Expr constExpr = exprList.get(i);
          // Disable codegen for const expressions which will only ever be evaluated once.
          if (!isInSubplan_) constExpr.disableCodegen();
          newExprList.add(constExpr);
        }
      }
      materializedConstExprLists_.add(newExprList);
    }
  }

  @Override
  protected void toThrift(TPlanNode msg) {