simpledb.record
Class RecordPage

java.lang.Object
  simpledb.record.RecordPage

public class RecordPage
extends java.lang.Object

Manages the placement and access of records in a block.

Author:

Edward Sciore

Field Summary

static int	EMPTY
static int	INUSE

Constructor Summary

RecordPage(Block blk, TableInfo ti, Transaction tx)
Creates the record manager for the specified block.

Method Summary

void	close() Closes the manager, by unpinning the block.
int	currentId() Returns the ID of the current record.
void	delete() Deletes the current record.
int	getInt(java.lang.String fldname) Returns the integer value stored for the specified field of the current record.
java.lang.String	getString(java.lang.String fldname) Returns the string value stored for the specified field of the current record.
boolean	insert() Inserts a new, blank record somewhere in the page.
void	moveToId(int id) Sets the current record to be the record having the specified ID.
boolean	next() Moves to the next record in the block.
void	setInt(java.lang.String fldname, int val) Stores an integer at the specified field of the current record.
void	setString(java.lang.String fldname, java.lang.String val) Stores a string at the specified field of the current record.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final int EMPTY

See Also:

Constant Field Values

INUSE

public static final int INUSE

See Also:

Constant Field Values

Constructor Detail

RecordPage

public RecordPage(Block blk,
                  TableInfo ti,
                  Transaction tx)

Creates the record manager for the specified block. The current record is set to be prior to the first one.

Parameters:

blk - a reference to the disk block

ti - the table's metadata

tx - the transaction performing the operations

Method Detail

close

public void close()

Closes the manager, by unpinning the block.

next

public boolean next()

Moves to the next record in the block.

Returns:

false if there is no next record.

getInt

public int getInt(java.lang.String fldname)

Returns the integer value stored for the specified field of the current record.

Parameters:

fldname - the name of the field.

Returns:

the integer stored in that field

getString

public java.lang.String getString(java.lang.String fldname)

Returns the string value stored for the specified field of the current record.

Parameters:

fldname - the name of the field.

Returns:

the string stored in that field

setInt

public void setInt(java.lang.String fldname,
                   int val)

Stores an integer at the specified field of the current record.

Parameters:

fldname - the name of the field

val - the integer value stored in that field

setString

public void setString(java.lang.String fldname,
                      java.lang.String val)

Stores a string at the specified field of the current record.

Parameters:

fldname - the name of the field

val - the string value stored in that field

delete

public void delete()

Deletes the current record. Deletion is performed by just marking the record as "deleted"; the current record does not change. To get to the next record, call next().

insert

public boolean insert()

Inserts a new, blank record somewhere in the page. Return false if there were no available slots.

Returns:

false if the insertion was not possible

moveToId

public void moveToId(int id)

Sets the current record to be the record having the specified ID.

Parameters:

id - the ID of the record within the page.

currentId

public int currentId()

Returns the ID of the current record.

Returns:

the ID of the current record