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);
  }
示例#2
0
文件: RexUtil.java 项目: kunlqt/optiq
 /**
  * Creates a key for {@link RexNode} which is the same as another key of another RexNode only if
  * the two have both the same type and textual representation. For example, "10" integer and "10"
  * bigint result in different keys.
  */
 public static String makeKey(RexNode expr) {
   String type = expr.getType().getFullTypeString();
   String separator = ";";
   String node = expr.toString();
   StringBuilder keyBuilder =
       new StringBuilder(type.length() + separator.length() + node.length());
   keyBuilder.append(type).append(separator).append(node);
   return keyBuilder.toString();
 }
  /**
   * Determines if a projection is simple.
   *
   * @param calcRel CalcRel containing the projection
   * @param projOrdinals if the projection is simple, returns the ordinals of the projection inputs
   * @return rowtype corresponding to the projection, provided it is simple; otherwise null is
   *     returned
   */
  private RelDataType isProjectSimple(CalcRel calcRel, List<Integer> projOrdinals) {
    // Loop through projection expressions.  If we find a non-simple
    // projection expression, simply return.
    RexProgram program = calcRel.getProgram();
    List<RexLocalRef> projList = program.getProjectList();
    int nProjExprs = projList.size();
    RelDataType[] types = new RelDataType[nProjExprs];
    String[] fieldNames = new String[nProjExprs];
    RelDataTypeField[] projFields = calcRel.getRowType().getFields();

    for (int i = 0; i < nProjExprs; i++) {
      RexNode projExpr = program.expandLocalRef(projList.get(i));
      if (projExpr instanceof RexInputRef) {
        projOrdinals.add(((RexInputRef) projExpr).getIndex());
        types[i] = projExpr.getType();
        fieldNames[i] = projFields[i].getName();
        continue;
      } else if (!(projExpr instanceof RexCall)) {
        return null;
      }

      RexCall rexCall = (RexCall) projExpr;
      if (rexCall.getOperator() != SqlStdOperatorTable.castFunc) {
        return null;
      }
      RexNode castOperand = rexCall.getOperands()[0];
      if (!(castOperand instanceof RexInputRef)) {
        return null;
      }
      RelDataType castType = projExpr.getType();
      RelDataType origType = castOperand.getType();
      if (isCastSimple(origType, castType)) {
        projOrdinals.add(((RexInputRef) castOperand).getIndex());
        types[i] = castType;
        fieldNames[i] = projFields[i].getName();
      } else {
        return null;
      }
    }

    // return the rowtype corresponding to the output of the projection
    return calcRel.getCluster().getTypeFactory().createStructType(types, fieldNames);
  }
 // override RexShuttle
 public RexNode visitCall(final RexCall call) {
   int i = reducibleExps.indexOf(call);
   if (i == -1) {
     return super.visitCall(call);
   }
   RexNode replacement = reducedValues.get(i);
   if (addCasts.get(i) && (replacement.getType() != call.getType())) {
     // Handle change from nullable to NOT NULL by claiming
     // that the result is still nullable, even though
     // we know it isn't.
     //
     // Also, we cannot reduce CAST('abc' AS VARCHAR(4)) to 'abc'.
     // If we make 'abc' of type VARCHAR(4), we may later encounter
     // the same expression in a ProjectRel's digest where it has
     // type VARCHAR(3), and that's wrong.
     replacement = rexBuilder.makeCast(call.getType(), replacement);
   }
   return replacement;
 }
  protected void executeImpl() throws Exception {
    SqlCall call = (SqlCall) subq;
    SqlSelect select = (SqlSelect) call.getOperands()[0];

    // Convert the SqlNode tree to a RelNode tree; we need to do this
    // here so the RelNode tree is associated with the new preparing
    // stmt.
    FarragoPreparingStmt preparingStmt = (FarragoPreparingStmt) getPreparingStmt();
    SqlValidator validator = preparingStmt.getSqlValidator();
    SqlToRelConverter sqlConverter = preparingStmt.getSqlToRelConverter(validator, preparingStmt);
    preparingStmt.setParentStmt(FennelRelUtil.getPreparingStmt(parentConverter.getCluster()));

    // Add to the new converter any subqueries that have already been
    // converted by the parent so we can avoid re-executing them
    sqlConverter.addConvertedNonCorrSubqs(parentConverter.getMapConvertedNonCorrSubqs());
    RelNode plan = sqlConverter.convertQuery(select, true, true);

    // The subquery cannot have dynamic parameters
    if (sqlConverter.getDynamicParamCount() > 0) {
      failed = true;
      return;
    }

    List<RexNode> exprs = new ArrayList<RexNode>();
    RelDataType resultType = null;

    if (!isExists) {
      // Non-EXISTS subqueries need to be converted to single-value
      // subqueries
      plan = sqlConverter.convertToSingleValueSubq(select, plan);

      // Create a dummy expression to store the type of the result.
      // When setting the type, derive the type based on what a
      // scalar subquery should return and create the type from the
      // type factory of the parent query.
      resultType = call.getOperator().deriveType(validator, validator.getFromScope(select), call);
      resultType = rexBuilder.getTypeFactory().copyType(resultType);
      exprs.add(rexBuilder.makeInputRef(resultType, 0));
    }

    plan = sqlConverter.decorrelate(select, plan);

    // If the subquery is part of an EXPLAIN PLAN statement, don't
    // execute the subquery, but instead just return a dynamic parameter
    // as a placeholder for the subquery result.  Otherwise, execute
    // the query to produce the constant expression.  Cast the expression
    // as needed so the type matches the expected result type.
    RexNode constExpr;
    if (isExplain) {
      if (isExists) {
        resultType = rexBuilder.getTypeFactory().createSqlType(SqlTypeName.BOOLEAN);
      }
      constExpr =
          rexBuilder.makeDynamicParam(
              resultType, parentConverter.getDynamicParamCountInExplain(true));
      results.add(constExpr);
    } else {
      executePlan(plan, exprs, isExists, false);
      if (!failed && !isExists) {
        constExpr = results.get(0);
        if (constExpr.getType() != resultType) {
          constExpr = rexBuilder.makeCast(resultType, constExpr);
          results.set(0, constExpr);
        }
      }
    }
  }