simpledb

Class Rename

java.lang.Object

simpledb.Operator

simpledb.Rename

All Implemented Interfaces:

java.io.Serializable, DbIterator

public class Rename
extends Operator

Only used in lab6.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private DbIterator	child
private int	inField
private java.lang.String	newName
private static long	serialVersionUID
private TupleDesc	td

Constructor Summary

Constructors

Constructor and Description
Rename(int inField, java.lang.String newName, DbIterator child)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes this iterator.
protected Tuple	fetchNext() Returns the next Tuple in the iterator, or null if the iteration is finished.
DbIterator[]	getChildren()
TupleDesc	getTupleDesc() Returns the TupleDesc associated with this DbIterator.
java.lang.String	newName()
void	open() Opens the iterator.
int	renamedField()
void	rewind() Resets the iterator to the start.
void	setChildren(DbIterator[] children) Set the children(child) of this operator.
private void	updateTD()

Methods inherited from class simpledb.Operator

getEstimatedCardinality, hasNext, next, setEstimatedCardinality

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

inField

private int inField

newName

private java.lang.String newName

child

private DbIterator child

td

private TupleDesc td

Constructor Detail

Rename

public Rename(int inField,
      java.lang.String newName,
      DbIterator child)

Method Detail

newName

public java.lang.String newName()

renamedField

public int renamedField()

open

public void open()
          throws DbException,
                 TransactionAbortedException

Description copied from interface: DbIterator

Opens the iterator. This must be called before any of the other methods.

Specified by:

open in interface DbIterator

Overrides:

open in class Operator

Throws:

DbException - when there are problems opening/accessing the database.

TransactionAbortedException

close

public void close()

Description copied from class: Operator

Closes this iterator. If overridden by a subclass, they should call super.close() in order for Operator's internal state to be consistent.

Specified by:

close in interface DbIterator

Overrides:

close in class Operator

rewind

public void rewind()
            throws DbException,
                   TransactionAbortedException

Description copied from interface: DbIterator

Resets the iterator to the start.

Throws:

DbException - when rewind is unsupported.

TransactionAbortedException

fetchNext

protected Tuple fetchNext()
                   throws DbException,
                          TransactionAbortedException

Description copied from class: Operator

Returns the next Tuple in the iterator, or null if the iteration is finished. Operator uses this method to implement both next and hasNext.

Specified by:

fetchNext in class Operator

Returns:

the next Tuple in the iterator, or null if the iteration is finished.

Throws:

DbException

TransactionAbortedException

getChildren

public DbIterator[] getChildren()

Specified by:

getChildren in class Operator

Returns:

return the children DbIterators of this operator. If there is only one child, return an array of only one element. For join operators, the order of the children is not important. But they should be consistent among multiple calls.

setChildren

public void setChildren(DbIterator[] children)

Description copied from class: Operator

Set the children(child) of this operator. If the operator has only one child, children[0] should be used. If the operator is a join, children[0] and children[1] should be used.

Specified by:

setChildren in class Operator

Parameters:

children - the DbIterators which are to be set as the children(child) of this operator

getTupleDesc

public TupleDesc getTupleDesc()

Description copied from interface: DbIterator

Returns the TupleDesc associated with this DbIterator.

Specified by:

getTupleDesc in interface DbIterator

Specified by:

getTupleDesc in class Operator

Returns:

return the TupleDesc of the output tuples of this operator

updateTD

private void updateTD()