/**
   * Creates projection list for scan. If the projection contains expressions, then the input
   * references from those expressions are extracted and that list of references becomes the
   * projection list.
   *
   * @param origScan row scan underneath the project
   * @param projRel ProjectRel that we will be creating the projection for
   * @param projectedColumns returns a list of the projected column ordinals, if it is possible to
   *     project
   * @param preserveExprCondition condition that identifies special expressions that should be
   *     preserved in the projection
   * @param defaultExpr expression to be used in the projection if no fields or special columns are
   *     selected
   * @param newProjList returns a new projection RelNode corresponding to a projection that now
   *     references a rowscan that is projecting the input references that were extracted from the
   *     original projection expressions; if the original expression didn't contain expressions,
   *     then this list is returned empty
   * @return true if columns in projection list from the scan need to be renamed
   */
  public boolean createProjectionList(
      FennelRel origScan,
      ProjectRel projRel,
      List<Integer> projectedColumns,
      PushProjector.ExprCondition preserveExprCondition,
      RexNode defaultExpr,
      List<ProjectRel> newProjList) {
    // REVIEW:  what about AnonFields?
    int n = projRel.getChildExps().length;
    RelDataType rowType = origScan.getRowType();
    RelDataType projType = projRel.getRowType();
    RelDataTypeField[] projFields = projType.getFields();
    List<Integer> tempProjList = new ArrayList<Integer>();
    boolean needRename = false;
    for (int i = 0; i < n; ++i) {
      RexNode exp = projRel.getChildExps()[i];
      List<String> origFieldName = new ArrayList<String>();
      Integer projIndex = mapProjCol(exp, origFieldName, rowType);
      if (projIndex == null) {
        // there are expressions in the projection; we need to extract
        // all input references and any special expressions from the
        // projection
        PushProjector pushProject =
            new PushProjector(projRel, null, origScan, preserveExprCondition);
        ProjectRel newProject = pushProject.convertProject(defaultExpr);
        if (newProject == null) {
          // can't do any further projection
          return false;
        }
        newProjList.add(newProject);

        // using the input references we just extracted, it should now
        // be possible to create a projection for the row scan
        needRename =
            createProjectionList(
                origScan,
                (ProjectRel) newProject.getChild(),
                projectedColumns,
                preserveExprCondition,
                defaultExpr,
                newProjList);
        assert (projectedColumns.size() > 0);
        return needRename;
      }
      String projFieldName = projFields[i].getName();
      if (!projFieldName.equals(origFieldName.get(0))) {
        needRename = true;
      }
      tempProjList.add(projIndex);
    }

    // now that we've determined it is possible to project, add the
    // ordinals to the return list
    projectedColumns.addAll(tempProjList);
    return needRename;
  }
  /**
   * Creates new RelNodes replacing/removing the original project/row scan
   *
   * @param projectedScan new scan that is now projected
   * @param origProject original projection
   * @param needRename true if fields from the row scan need to be renamed
   * @param newProject projection that contains the new projection expressions, in the case where
   *     the original projection cannot be removed because it projects expressions
   * @return new RelNode
   */
  public RelNode createNewRelNode(
      RelNode projectedScan, ProjectRel origProject, boolean needRename, ProjectRel newProject) {
    RelNode scanRel;
    if (needRename) {
      // Replace calling convention with FENNEL_EXEC_CONVENTION
      RelTraitSet traits = RelOptUtil.clone(origProject.getTraits());
      traits.setTrait(CallingConventionTraitDef.instance, FennelRel.FENNEL_EXEC_CONVENTION);
      if (!traits.equals(projectedScan.getTraits())) {
        RelNode mergedProjectedScan = convert(projectedScan, traits);
        RelOptPlanner planner = projectedScan.getCluster().getPlanner();
        // register projectedScan == mergedProjectedScan
        // so mergedProjectedScan will have a set later on
        projectedScan = planner.ensureRegistered(mergedProjectedScan, projectedScan);
      }
      scanRel =
          new FennelRenameRel(
              origProject.getCluster(),
              projectedScan,
              RelOptUtil.getFieldNames(origProject.getRowType()),
              traits);
    } else {
      scanRel = projectedScan;
    }

    if (newProject == null) {
      return scanRel;
    } else {
      // in the case where the projection had expressions, put the
      // new, modified projection on top of the projected row scan
      return (ProjectRel)
          CalcRel.createProject(
              scanRel,
              newProject.getProjectExps(),
              RelOptUtil.getFieldNames(newProject.getRowType()));
    }
  }
        public void onMatch(RelOptRuleCall call) {
          ProjectRel project = (ProjectRel) call.rels[0];
          List<RexNode> expList = new ArrayList<RexNode>(Arrays.asList(project.getChildExps()));
          if (reduceExpressions(project, expList)) {
            call.transformTo(
                new ProjectRel(
                    project.getCluster(),
                    project.getChild(),
                    expList.toArray(new RexNode[expList.size()]),
                    project.getRowType(),
                    ProjectRel.Flags.Boxed,
                    Collections.<RelCollation>emptyList()));

            // New plan is absolutely better than old plan.
            call.getPlanner().setImportance(project, 0.0);
          }
        }
Exemplo n.º 4
0
  /** Variant of {@link #trimFields(RelNode, BitSet, Set)} for {@link ProjectRel}. */
  public TrimResult trimFields(
      ProjectRel project, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
    final RelDataType rowType = project.getRowType();
    final int fieldCount = rowType.getFieldCount();
    final RelNode input = project.getChild();
    final RelDataType inputRowType = input.getRowType();

    // Which fields are required from the input?
    BitSet inputFieldsUsed = new BitSet(inputRowType.getFieldCount());
    final Set<RelDataTypeField> inputExtraFields = new LinkedHashSet<RelDataTypeField>(extraFields);
    RelOptUtil.InputFinder inputFinder =
        new RelOptUtil.InputFinder(inputFieldsUsed, inputExtraFields);
    for (Ord<RexNode> ord : Ord.zip(project.getProjects())) {
      if (fieldsUsed.get(ord.i)) {
        ord.e.accept(inputFinder);
      }
    }

    // Create input with trimmed columns.
    TrimResult trimResult = trimChild(project, input, inputFieldsUsed, inputExtraFields);
    RelNode newInput = trimResult.left;
    final Mapping inputMapping = trimResult.right;

    // If the input is unchanged, and we need to project all columns,
    // there's nothing we can do.
    if (newInput == input && fieldsUsed.cardinality() == fieldCount) {
      return new TrimResult(project, Mappings.createIdentity(fieldCount));
    }

    // Some parts of the system can't handle rows with zero fields, so
    // pretend that one field is used.
    if (fieldsUsed.cardinality() == 0) {
      final Mapping mapping = Mappings.create(MappingType.InverseSurjection, fieldCount, 1);
      final RexLiteral expr =
          project.getCluster().getRexBuilder().makeExactLiteral(BigDecimal.ZERO);
      RelDataType newRowType =
          project
              .getCluster()
              .getTypeFactory()
              .createStructType(
                  Collections.singletonList(expr.getType()), Collections.singletonList("DUMMY"));
      ProjectRel newProject =
          new ProjectRel(
              project.getCluster(),
              project.getCluster().traitSetOf(RelCollationImpl.EMPTY),
              newInput,
              Collections.<RexNode>singletonList(expr),
              newRowType,
              project.getFlags());
      return new TrimResult(newProject, mapping);
    }

    // Build new project expressions, and populate the mapping.
    List<RexNode> newProjectExprList = new ArrayList<RexNode>();
    final RexVisitor<RexNode> shuttle = new RexPermuteInputsShuttle(inputMapping, newInput);
    final Mapping mapping =
        Mappings.create(MappingType.InverseSurjection, fieldCount, fieldsUsed.cardinality());
    for (Ord<RexNode> ord : Ord.zip(project.getProjects())) {
      if (fieldsUsed.get(ord.i)) {
        mapping.set(ord.i, newProjectExprList.size());
        RexNode newProjectExpr = ord.e.accept(shuttle);
        newProjectExprList.add(newProjectExpr);
      }
    }

    final RelDataType newRowType =
        project
            .getCluster()
            .getTypeFactory()
            .createStructType(Mappings.apply3(mapping, rowType.getFieldList()));

    final List<RelCollation> newCollations =
        RexUtil.apply(inputMapping, project.getCollationList());

    final RelNode newProject;
    if (RemoveTrivialProjectRule.isIdentity(
        newProjectExprList, newRowType, newInput.getRowType())) {
      // The new project would be the identity. It is equivalent to return
      // its child.
      newProject = newInput;
    } else {
      newProject =
          new ProjectRel(
              project.getCluster(),
              project
                  .getCluster()
                  .traitSetOf(
                      newCollations.isEmpty() ? RelCollationImpl.EMPTY : newCollations.get(0)),
              newInput,
              newProjectExprList,
              newRowType,
              project.getFlags());
      assert newProject.getClass() == project.getClass();
    }
    return new TrimResult(newProject, mapping);
  }