示例#1
0
文件: RexUtil.java 项目: kunlqt/optiq
 /**
  * Generates a cast from one row type to another
  *
  * @param rexBuilder RexBuilder to use for constructing casts
  * @param lhsRowType target row type
  * @param rhsRowType source row type; fields must be 1-to-1 with lhsRowType, in same order
  * @return cast expressions
  */
 public static RexNode[] generateCastExpressions(
     RexBuilder rexBuilder, RelDataType lhsRowType, RelDataType rhsRowType) {
   int n = rhsRowType.getFieldCount();
   assert n == lhsRowType.getFieldCount()
       : "field count: lhs [" + lhsRowType + "] rhs [" + rhsRowType + "]";
   RexNode[] rhsExps = new RexNode[n];
   for (int i = 0; i < n; ++i) {
     rhsExps[i] = rexBuilder.makeInputRef(rhsRowType.getFields()[i].getType(), i);
   }
   return generateCastExpressions(rexBuilder, lhsRowType, rhsExps);
 }
示例#2
0
 /**
  * Trims a child relational expression, then adds back a dummy project to restore the fields that
  * were removed.
  *
  * <p>Sounds pointless? It causes unused fields to be removed further down the tree (towards the
  * leaves), but it ensure that the consuming relational expression continues to see the same
  * fields.
  *
  * @param rel Relational expression
  * @param input Input relational expression, whose fields to trim
  * @param fieldsUsed Bitmap of fields needed by the consumer
  * @return New relational expression and its field mapping
  */
 protected TrimResult trimChildRestore(
     RelNode rel, RelNode input, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
   TrimResult trimResult = trimChild(rel, input, fieldsUsed, extraFields);
   if (trimResult.right.isIdentity()) {
     return trimResult;
   }
   final RelDataType rowType = input.getRowType();
   List<RelDataTypeField> fieldList = rowType.getFieldList();
   final List<RexNode> exprList = new ArrayList<RexNode>();
   final List<String> nameList = rowType.getFieldNames();
   RexBuilder rexBuilder = rel.getCluster().getRexBuilder();
   assert trimResult.right.getSourceCount() == fieldList.size();
   for (int i = 0; i < fieldList.size(); i++) {
     int source = trimResult.right.getTargetOpt(i);
     RelDataTypeField field = fieldList.get(i);
     exprList.add(
         source < 0
             ? rexBuilder.makeZeroLiteral(field.getType())
             : rexBuilder.makeInputRef(field.getType(), source));
   }
   RelNode project = CalcRel.createProject(trimResult.left, exprList, nameList);
   return new TrimResult(project, Mappings.createIdentity(fieldList.size()));
 }