Beispiel #1
0
  @Override
  protected RelationPlan visitUnion(Union node, Void context) {
    checkArgument(!node.getRelations().isEmpty(), "No relations specified for UNION");

    List<Symbol> unionOutputSymbols = null;
    ImmutableList.Builder<PlanNode> sources = ImmutableList.builder();
    ImmutableListMultimap.Builder<Symbol, Symbol> symbolMapping = ImmutableListMultimap.builder();
    List<RelationPlan> subPlans =
        node.getRelations()
            .stream()
            .map(relation -> processAndCoerceIfNecessary(relation, context))
            .collect(toImmutableList());

    boolean hasSampleWeight = false;
    for (RelationPlan subPlan : subPlans) {
      if (subPlan.getSampleWeight().isPresent()) {
        hasSampleWeight = true;
        break;
      }
    }

    Optional<Symbol> outputSampleWeight = Optional.empty();
    for (RelationPlan relationPlan : subPlans) {
      if (hasSampleWeight && !relationPlan.getSampleWeight().isPresent()) {
        relationPlan = addConstantSampleWeight(relationPlan);
      }

      List<Symbol> childOutputSymbols = relationPlan.getOutputSymbols();
      if (unionOutputSymbols == null) {
        // Use the first Relation to derive output symbol names
        TupleDescriptor descriptor = relationPlan.getDescriptor();
        ImmutableList.Builder<Symbol> outputSymbolBuilder = ImmutableList.builder();
        for (Field field : descriptor.getVisibleFields()) {
          int fieldIndex = descriptor.indexOf(field);
          Symbol symbol = childOutputSymbols.get(fieldIndex);
          outputSymbolBuilder.add(
              symbolAllocator.newSymbol(symbol.getName(), symbolAllocator.getTypes().get(symbol)));
        }
        unionOutputSymbols = outputSymbolBuilder.build();
        outputSampleWeight = relationPlan.getSampleWeight();
      }

      TupleDescriptor descriptor = relationPlan.getDescriptor();
      checkArgument(
          descriptor.getVisibleFieldCount() == unionOutputSymbols.size(),
          "Expected relation to have %s symbols but has %s symbols",
          descriptor.getVisibleFieldCount(),
          unionOutputSymbols.size());

      int unionFieldId = 0;
      for (Field field : descriptor.getVisibleFields()) {
        int fieldIndex = descriptor.indexOf(field);
        symbolMapping.put(unionOutputSymbols.get(unionFieldId), childOutputSymbols.get(fieldIndex));
        unionFieldId++;
      }

      sources.add(relationPlan.getRoot());
    }

    PlanNode planNode =
        new UnionNode(idAllocator.getNextId(), sources.build(), symbolMapping.build());
    if (node.isDistinct()) {
      planNode = distinct(planNode);
    }
    return new RelationPlan(
        planNode,
        analysis.getOutputDescriptor(node),
        planNode.getOutputSymbols(),
        outputSampleWeight);
  }