/**
   * 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;
  }
コード例 #2
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  public Boolean areColumnsUnique(ProjectRelBase rel, BitSet columns, boolean ignoreNulls) {
    // ProjectRel maps a set of rows to a different set;
    // Without knowledge of the mapping function(whether it
    // preserves uniqueness), it is only safe to derive uniqueness
    // info from the child of a project when the mapping is f(a) => a.
    //
    // Also need to map the input column set to the corresponding child
    // references

    List<RexNode> projExprs = rel.getProjects();
    BitSet childColumns = new BitSet();
    for (int bit : BitSets.toIter(columns)) {
      RexNode projExpr = projExprs.get(bit);
      if (projExpr instanceof RexInputRef) {
        childColumns.set(((RexInputRef) projExpr).getIndex());
      } else if (projExpr instanceof RexCall && ignoreNulls) {
        // If the expression is a cast such that the types are the same
        // except for the nullability, then if we're ignoring nulls,
        // it doesn't matter whether the underlying column reference
        // is nullable.  Check that the types are the same by making a
        // nullable copy of both types and then comparing them.
        RexCall call = (RexCall) projExpr;
        if (call.getOperator() != SqlStdOperatorTable.CAST) {
          continue;
        }
        RexNode castOperand = call.getOperands().get(0);
        if (!(castOperand instanceof RexInputRef)) {
          continue;
        }
        RelDataTypeFactory typeFactory = rel.getCluster().getTypeFactory();
        RelDataType castType = typeFactory.createTypeWithNullability(projExpr.getType(), true);
        RelDataType origType = typeFactory.createTypeWithNullability(castOperand.getType(), true);
        if (castType.equals(origType)) {
          childColumns.set(((RexInputRef) castOperand).getIndex());
        }
      } else {
        // If the expression will not influence uniqueness of the
        // projection, then skip it.
        continue;
      }
    }

    // If no columns can affect uniqueness, then return unknown
    if (childColumns.cardinality() == 0) {
      return null;
    }

    return RelMetadataQuery.areColumnsUnique(rel.getChild(), childColumns, ignoreNulls);
  }
 protected Integer mapFieldRef(RexNode exp, List<String> origFieldName, RelDataType rowType) {
   RexInputRef fieldAccess = (RexInputRef) exp;
   origFieldName.add(rowType.getFields()[fieldAccess.getIndex()].getName());
   return fieldAccess.getIndex();
 }