simpledb
Class HeapPageId

java.lang.Object
  simpledb.HeapPageId

All Implemented Interfaces:

PageId

public class HeapPageId
extends java.lang.Object
implements PageId

Unique identifier for HeapPage objects.

Constructor Summary

HeapPageId(int tableId, int pgNo)
Constructor.

Method Summary

boolean	equals(java.lang.Object o) Compares one PageId to another.
int	getTableId()
int	hashCode()
int	pageNumber()
int[]	serialize() Return a representation of this object as an array of integers, for writing to disk.

Methods inherited from class java.lang.Object

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

Constructor Detail

HeapPageId

public HeapPageId(int tableId,
                  int pgNo)

Constructor. Create a page id structure for a specific page of a specific table.

Parameters:

tableId - The table that is being referenced

pgNo - The page number in that table.

Method Detail

getTableId

public int getTableId()

Specified by:

getTableId in interface PageId

Returns:

the table associated with this PageId

pageNumber

public int pageNumber()

Specified by:

pageNumber in interface PageId

Returns:

the page number in the table getTableId() associated with this PageId

hashCode

public int hashCode()

Specified by:

hashCode in interface PageId

Overrides:

hashCode in class java.lang.Object

Returns:

a hash code for this page, represented by the concatenation of the table number and the page number (needed if a PageId is used as a key in a hash table in the BufferPool, for example.)

See Also:

BufferPool

equals

public boolean equals(java.lang.Object o)

Compares one PageId to another.

Specified by:

equals in interface PageId

Overrides:

equals in class java.lang.Object

Parameters:

o - The object to compare against (must be a PageId)

Returns:

true if the objects are equal (e.g., page numbers and table ids are the same)

serialize

public int[] serialize()

Return a representation of this object as an array of integers, for writing to disk. Size of returned array must contain number of integers that corresponds to number of args to one of the constructors.

Specified by:

serialize in interface PageId