public void onMatch(RelOptRuleCall call) {
    assert matches(call);
    final JoinRel join = (JoinRel) call.rels[0];
    final List<Integer> leftKeys = new ArrayList<Integer>();
    final List<Integer> rightKeys = new ArrayList<Integer>();
    RelNode right = join.getRight();
    final RelNode left = join.getLeft();
    RexNode remainingCondition =
        RelOptUtil.splitJoinCondition(left, right, join.getCondition(), leftKeys, rightKeys);
    assert leftKeys.size() == rightKeys.size();
    final List<CorrelatorRel.Correlation> correlationList =
        new ArrayList<CorrelatorRel.Correlation>();
    if (leftKeys.size() > 0) {
      final RelOptCluster cluster = join.getCluster();
      final RexBuilder rexBuilder = cluster.getRexBuilder();
      int k = 0;
      RexNode condition = null;
      for (Integer leftKey : leftKeys) {
        Integer rightKey = rightKeys.get(k++);
        final String dyn_inIdStr = cluster.getQuery().createCorrel();
        final int dyn_inId = RelOptQuery.getCorrelOrdinal(dyn_inIdStr);

        // Create correlation to say 'each row, set variable #id
        // to the value of column #leftKey'.
        correlationList.add(new CorrelatorRel.Correlation(dyn_inId, leftKey));
        condition =
            RelOptUtil.andJoinFilters(
                rexBuilder,
                condition,
                rexBuilder.makeCall(
                    SqlStdOperatorTable.equalsOperator,
                    rexBuilder.makeInputRef(
                        right.getRowType().getFieldList().get(rightKey).getType(), rightKey),
                    rexBuilder.makeCorrel(
                        left.getRowType().getFieldList().get(leftKey).getType(), dyn_inIdStr)));
      }
      right = CalcRel.createFilter(right, condition);
    }
    RelNode newRel =
        new CorrelatorRel(
            join.getCluster(),
            left,
            right,
            remainingCondition,
            correlationList,
            join.getJoinType());
    call.transformTo(newRel);
  }
Exemple #2
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  /** Variant of {@link #trimFields(RelNode, BitSet, Set)} for {@link JoinRel}. */
  public TrimResult trimFields(JoinRel join, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
    final RelDataType rowType = join.getRowType();
    final int fieldCount = rowType.getFieldCount();
    final RexNode conditionExpr = join.getCondition();
    final int systemFieldCount = join.getSystemFieldList().size();

    // Add in fields used in the condition.
    BitSet fieldsUsedPlus = (BitSet) fieldsUsed.clone();
    final Set<RelDataTypeField> combinedInputExtraFields =
        new LinkedHashSet<RelDataTypeField>(extraFields);
    RelOptUtil.InputFinder inputFinder =
        new RelOptUtil.InputFinder(fieldsUsedPlus, combinedInputExtraFields);
    conditionExpr.accept(inputFinder);

    // If no system fields are used, we can remove them.
    int systemFieldUsedCount = 0;
    for (int i = 0; i < systemFieldCount; ++i) {
      if (fieldsUsed.get(i)) {
        ++systemFieldUsedCount;
      }
    }
    final int newSystemFieldCount;
    if (systemFieldUsedCount == 0) {
      newSystemFieldCount = 0;
    } else {
      newSystemFieldCount = systemFieldCount;
    }

    int offset = systemFieldCount;
    int changeCount = 0;
    int newFieldCount = newSystemFieldCount;
    List<RelNode> newInputs = new ArrayList<RelNode>(2);
    List<Mapping> inputMappings = new ArrayList<Mapping>();
    List<Integer> inputExtraFieldCounts = new ArrayList<Integer>();
    for (RelNode input : join.getInputs()) {
      final RelDataType inputRowType = input.getRowType();
      final int inputFieldCount = inputRowType.getFieldCount();

      // Compute required mapping.
      BitSet inputFieldsUsed = new BitSet(inputFieldCount);
      for (int bit : Util.toIter(fieldsUsedPlus)) {
        if (bit >= offset && bit < offset + inputFieldCount) {
          inputFieldsUsed.set(bit - offset);
        }
      }

      // If there are system fields, we automatically use the
      // corresponding field in each input.
      if (newSystemFieldCount > 0) {
        // calling with newSystemFieldCount == 0 should be safe but hits
        // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6222207
        inputFieldsUsed.set(0, newSystemFieldCount);
      }

      // FIXME: We ought to collect extra fields for each input
      // individually. For now, we assume that just one input has
      // on-demand fields.
      Set<RelDataTypeField> inputExtraFields =
          input.getRowType().getField("_extra") == null
              ? Collections.<RelDataTypeField>emptySet()
              : combinedInputExtraFields;
      inputExtraFieldCounts.add(inputExtraFields.size());
      TrimResult trimResult = trimChild(join, input, inputFieldsUsed, inputExtraFields);
      newInputs.add(trimResult.left);
      if (trimResult.left != input) {
        ++changeCount;
      }

      final Mapping inputMapping = trimResult.right;
      inputMappings.add(inputMapping);

      // Move offset to point to start of next input.
      offset += inputFieldCount;
      newFieldCount += inputMapping.getTargetCount() + inputExtraFields.size();
    }

    Mapping mapping = Mappings.create(MappingType.InverseSurjection, fieldCount, newFieldCount);
    for (int i = 0; i < newSystemFieldCount; ++i) {
      mapping.set(i, i);
    }
    offset = systemFieldCount;
    int newOffset = newSystemFieldCount;
    for (int i = 0; i < inputMappings.size(); i++) {
      Mapping inputMapping = inputMappings.get(i);
      for (IntPair pair : inputMapping) {
        mapping.set(pair.source + offset, pair.target + newOffset);
      }
      offset += inputMapping.getSourceCount();
      newOffset += inputMapping.getTargetCount() + inputExtraFieldCounts.get(i);
    }

    if (changeCount == 0 && mapping.isIdentity()) {
      return new TrimResult(join, Mappings.createIdentity(fieldCount));
    }

    // Build new join.
    final RexVisitor<RexNode> shuttle =
        new RexPermuteInputsShuttle(mapping, newInputs.get(0), newInputs.get(1));
    RexNode newConditionExpr = conditionExpr.accept(shuttle);

    final JoinRel newJoin =
        join.copy(join.getTraitSet(), newConditionExpr, newInputs.get(0), newInputs.get(1));

    return new TrimResult(newJoin, mapping);
  }