public void analyze(RexNode exp) {
      assert (stack.isEmpty());

      exp.accept(this);

      // Deal with top of stack
      assert (stack.size() == 1);
      assert (parentCallTypeStack.isEmpty());
      Constancy rootConstancy = stack.get(0);
      if (rootConstancy == Constancy.REDUCIBLE_CONSTANT) {
        // The entire subtree was constant, so add it to the result.
        addResult(exp);
      }
      stack.clear();
    }
Ejemplo n.º 2
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  /**
   * Applies a mapping to a collation list.
   *
   * @param mapping Mapping
   * @param collationList Collation list
   * @return collation list with mapping applied to each field
   */
  public static List<RelCollation> apply(
      Mappings.TargetMapping mapping, List<RelCollation> collationList) {
    final List<RelCollation> newCollationList = new ArrayList<RelCollation>();
    for (RelCollation collation : collationList) {
      final List<RelFieldCollation> newFieldCollationList = new ArrayList<RelFieldCollation>();
      for (RelFieldCollation fieldCollation : collation.getFieldCollations()) {
        final RelFieldCollation newFieldCollation = apply(mapping, fieldCollation);
        if (newFieldCollation == null) {
          // This field is not mapped. Stop here. The leading edge
          // of the collation is still valid (although it's useless
          // if it's empty).
          break;
        }
        newFieldCollationList.add(newFieldCollation);
      }
      // Truncation to collations to their leading edge creates empty
      // and duplicate collations. Ignore these.
      if (!newFieldCollationList.isEmpty()) {
        final RelCollationImpl newCollation = new RelCollationImpl(newFieldCollationList);
        if (!newCollationList.contains(newCollation)) {
          newCollationList.add(newCollation);
        }
      }
    }

    // REVIEW: There might be redundant collations in the list. For example,
    // in {(x), (x, y)}, (x) is redundant because it is a leading edge of
    // another collation in the list. Could remove redundant collations.

    return newCollationList;
  }
    private void addResult(RexNode exp) {
      // Cast of literal can't be reduced, so skip those (otherwise we'd
      // go into an infinite loop as we add them back).
      if (exp.getKind() == RexKind.Cast) {
        RexCall cast = (RexCall) exp;
        RexNode operand = cast.getOperands()[0];
        if (operand instanceof RexLiteral) {
          return;
        }
      }
      constExprs.add(exp);

      // In the case where the expression corresponds to a UDR argument,
      // we need to preserve casts.  Note that this only applies to
      // the topmost argument, not expressions nested within the UDR
      // call.
      //
      // REVIEW zfong 6/13/08 - Are there other expressions where we
      // also need to preserve casts?
      if (parentCallTypeStack.isEmpty()) {
        addCasts.add(false);
      } else {
        addCasts.add(
            parentCallTypeStack.get(parentCallTypeStack.size() - 1)
                instanceof FarragoUserDefinedRoutine);
      }
    }
Ejemplo n.º 4
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  /**
   * Creates an OR expression from a list of RexNodes
   *
   * @param rexList list of RexNodes
   * @return OR'd expression
   */
  public static RexNode orRexNodeList(RexBuilder rexBuilder, List<RexNode> rexList) {
    if (rexList.isEmpty()) {
      return null;
    }

    RexNode orExpr = rexList.get(rexList.size() - 1);
    for (int i = rexList.size() - 2; i >= 0; i--) {
      orExpr = rexBuilder.makeCall(SqlStdOperatorTable.orOperator, rexList.get(i), orExpr);
    }
    return orExpr;
  }
Ejemplo n.º 5
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  /**
   * Creates an AND expression from a list of RexNodes
   *
   * @param rexList list of RexNodes
   * @return AND'd expression
   */
  public static RexNode andRexNodeList(RexBuilder rexBuilder, List<RexNode> rexList) {
    if (rexList.isEmpty()) {
      return null;
    }

    // create a right-deep tree to allow short-circuiting during
    // expression evaluation
    RexNode andExpr = rexList.get(rexList.size() - 1);
    for (int i = rexList.size() - 2; i >= 0; i--) {
      andExpr = rexBuilder.makeCall(SqlStdOperatorTable.andOperator, rexList.get(i), andExpr);
    }
    return andExpr;
  }
  private void onMatchRight(RelOptRuleCall call) {
    final JoinRelBase topJoin = call.rel(0);
    final JoinRelBase bottomJoin = call.rel(1);
    final RelNode relC = call.rel(2);
    final RelNode relA = bottomJoin.getLeft();
    final RelNode relB = bottomJoin.getRight();
    final RelOptCluster cluster = topJoin.getCluster();

    //        topJoin
    //        /     \
    //   bottomJoin  C
    //    /    \
    //   A      B

    final int aCount = relA.getRowType().getFieldCount();
    final int bCount = relB.getRowType().getFieldCount();
    final int cCount = relC.getRowType().getFieldCount();
    final BitSet bBitSet = BitSets.range(aCount, aCount + bCount);

    // becomes
    //
    //        newTopJoin
    //        /        \
    //   newBottomJoin  B
    //    /    \
    //   A      C

    // If either join is not inner, we cannot proceed.
    // (Is this too strict?)
    if (topJoin.getJoinType() != JoinRelType.INNER
        || bottomJoin.getJoinType() != JoinRelType.INNER) {
      return;
    }

    // Split the condition of topJoin into a conjunction. Each of the
    // parts that does not use columns from B can be pushed down.
    final List<RexNode> intersecting = new ArrayList<RexNode>();
    final List<RexNode> nonIntersecting = new ArrayList<RexNode>();
    split(topJoin.getCondition(), bBitSet, intersecting, nonIntersecting);

    // If there's nothing to push down, it's not worth proceeding.
    if (nonIntersecting.isEmpty()) {
      return;
    }

    // Split the condition of bottomJoin into a conjunction. Each of the
    // parts that use columns from B will need to be pulled up.
    final List<RexNode> bottomIntersecting = new ArrayList<RexNode>();
    final List<RexNode> bottomNonIntersecting = new ArrayList<RexNode>();
    split(bottomJoin.getCondition(), bBitSet, bottomIntersecting, bottomNonIntersecting);

    // target: | A       | C      |
    // source: | A       | B | C      |
    final Mappings.TargetMapping bottomMapping =
        Mappings.createShiftMapping(
            aCount + bCount + cCount, 0, 0, aCount, aCount, aCount + bCount, cCount);
    List<RexNode> newBottomList = new ArrayList<RexNode>();
    new RexPermuteInputsShuttle(bottomMapping, relA, relC)
        .visitList(nonIntersecting, newBottomList);
    final Mappings.TargetMapping bottomBottomMapping =
        Mappings.createShiftMapping(aCount + bCount, 0, 0, aCount);
    new RexPermuteInputsShuttle(bottomBottomMapping, relA, relC)
        .visitList(bottomNonIntersecting, newBottomList);
    final RexBuilder rexBuilder = cluster.getRexBuilder();
    RexNode newBottomCondition = RexUtil.composeConjunction(rexBuilder, newBottomList, false);
    final JoinRelBase newBottomJoin =
        bottomJoin.copy(
            bottomJoin.getTraitSet(), newBottomCondition, relA, relC, bottomJoin.getJoinType());

    // target: | A       | C      | B |
    // source: | A       | B | C      |
    final Mappings.TargetMapping topMapping =
        Mappings.createShiftMapping(
            aCount + bCount + cCount,
            0,
            0,
            aCount,
            aCount + cCount,
            aCount,
            bCount,
            aCount,
            aCount + bCount,
            cCount);
    List<RexNode> newTopList = new ArrayList<RexNode>();
    new RexPermuteInputsShuttle(topMapping, newBottomJoin, relB)
        .visitList(intersecting, newTopList);
    new RexPermuteInputsShuttle(topMapping, newBottomJoin, relB)
        .visitList(bottomIntersecting, newTopList);
    RexNode newTopCondition = RexUtil.composeConjunction(rexBuilder, newTopList, false);
    @SuppressWarnings("SuspiciousNameCombination")
    final JoinRelBase newTopJoin =
        topJoin.copy(
            topJoin.getTraitSet(), newTopCondition, newBottomJoin, relB, topJoin.getJoinType());

    assert !Mappings.isIdentity(topMapping);
    final RelNode newProject =
        RelFactories.createProject(projectFactory, newTopJoin, Mappings.asList(topMapping));

    call.transformTo(newProject);
  }
Ejemplo n.º 7
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  /** 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);
  }
  /**
   * Reduces a list of expressions.
   *
   * @param rel Relational expression
   * @param expList List of expressions, modified in place
   * @return whether reduction found something to change, and succeeded
   */
  static boolean reduceExpressions(RelNode rel, List<RexNode> expList) {
    RexBuilder rexBuilder = rel.getCluster().getRexBuilder();

    // Find reducible expressions.
    FarragoSessionPlanner planner = (FarragoSessionPlanner) rel.getCluster().getPlanner();
    FarragoSessionPreparingStmt preparingStmt = planner.getPreparingStmt();
    List<RexNode> constExps = new ArrayList<RexNode>();
    List<Boolean> addCasts = new ArrayList<Boolean>();
    List<RexNode> removableCasts = new ArrayList<RexNode>();
    findReducibleExps(preparingStmt, expList, constExps, addCasts, removableCasts);
    if (constExps.isEmpty() && removableCasts.isEmpty()) {
      return false;
    }

    // Remove redundant casts before reducing constant expressions.
    // If the argument to the redundant cast is a reducible constant,
    // reducing that argument to a constant first will result in not being
    // able to locate the original cast expression.
    if (!removableCasts.isEmpty()) {
      List<RexNode> reducedExprs = new ArrayList<RexNode>();
      List<Boolean> noCasts = new ArrayList<Boolean>();
      for (RexNode exp : removableCasts) {
        RexCall call = (RexCall) exp;
        reducedExprs.add(call.getOperands()[0]);
        noCasts.add(false);
      }
      RexReplacer replacer = new RexReplacer(rexBuilder, removableCasts, reducedExprs, noCasts);
      replacer.apply(expList);
    }

    if (constExps.isEmpty()) {
      return true;
    }

    // Compute the values they reduce to.
    List<RexNode> reducedValues = new ArrayList<RexNode>();
    ReentrantValuesStmt reentrantStmt =
        new ReentrantValuesStmt(
            preparingStmt.getRootStmtContext(), rexBuilder, constExps, reducedValues);
    FarragoSession session = getSession(rel);
    reentrantStmt.execute(session, true);
    if (reentrantStmt.failed) {
      return false;
    }

    // For ProjectRel, we have to be sure to preserve the result
    // types, so always cast regardless of the expression type.
    // For other RelNodes like FilterRel, in general, this isn't necessary,
    // and the presence of casts could hinder other rules such as sarg
    // analysis, which require bare literals.  But there are special cases,
    // like when the expression is a UDR argument, that need to be
    // handled as special cases.
    if (rel instanceof ProjectRel) {
      for (int i = 0; i < reducedValues.size(); i++) {
        addCasts.set(i, true);
      }
    }

    RexReplacer replacer = new RexReplacer(rexBuilder, constExps, reducedValues, addCasts);
    replacer.apply(expList);
    return true;
  }