org.h2.store

Class Page

java.lang.Object

org.h2.util.CacheObject

org.h2.store.Page

All Implemented Interfaces:

Comparable<CacheObject>

Direct Known Subclasses:

PageBtree, PageDataLeaf, PageDataNode, PageDataOverflow, PageFreeList, PageStreamData, PageStreamTrunk

public abstract class Page
extends CacheObject

A page. Format:

• 0-3: parent page id (0 for root)
• 4-4: page type
• page-type specific data

Field Summary

Fields

Modifier and Type	Field and Description
protected int	changeCount When this page was changed the last time.
static int	FLAG_LAST This is the last page of a chain.
static int	TYPE_BTREE_LEAF A b-tree leaf page (without overflow: + FLAG_LAST).
static int	TYPE_BTREE_NODE A b-tree node page (never has overflow pages).
static int	TYPE_DATA_LEAF A data leaf page (without overflow: + FLAG_LAST).
static int	TYPE_DATA_NODE A data node page (never has overflow pages).
static int	TYPE_DATA_OVERFLOW A data overflow page (the last page: + FLAG_LAST).
static int	TYPE_EMPTY An empty page.
static int	TYPE_FREE_LIST A page containing a list of free pages (the last page: + FLAG_LAST).
static int	TYPE_STREAM_DATA A stream data page.
static int	TYPE_STREAM_TRUNK A stream trunk page.

Fields inherited from class org.h2.util.CacheObject

cacheChained, cacheNext, cachePrevious

Constructor Summary

Constructors

Constructor and Description
Page()

Method Summary

Methods

Modifier and Type	Method and Description
protected static void	add(int[] array, int from, int to, int x) Add a value to a subset of the array.
boolean	canMove() If this page can be moved.
protected static int[]	insert(int[] old, int oldSize, int pos, int x) Insert a value in an array.
protected static long[]	insert(long[] old, int oldSize, int pos, long x) Insert a value in an array.
static <T> T[]	insert(T[] old, int oldSize, int pos, T x) Insert a value in an array.
abstract void	moveTo(Session session, int newPos) Copy the data to a new location, change the parent to point to the new location, and free up the current page.
protected static int[]	remove(int[] old, int oldSize, int pos) Delete a value in an array.
protected static long[]	remove(long[] old, int oldSize, int pos) Delete a value in an array.
static <T> T[]	remove(T[] old, int oldSize, int pos) Delete a value in an array.
abstract void	write() Write the page.

Methods inherited from class org.h2.util.CacheObject

canRemove, compareTo, getMemory, getPos, isChanged, isStream, setChanged, setPos

Methods inherited from class java.lang.Object

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

Field Detail

FLAG_LAST

public static final int FLAG_LAST

This is the last page of a chain.

See Also:

Constant Field Values

TYPE_EMPTY

public static final int TYPE_EMPTY

An empty page.

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Constant Field Values

TYPE_DATA_LEAF

public static final int TYPE_DATA_LEAF

A data leaf page (without overflow: + FLAG_LAST).

See Also:

Constant Field Values

TYPE_DATA_NODE

public static final int TYPE_DATA_NODE

A data node page (never has overflow pages).

See Also:

Constant Field Values

TYPE_DATA_OVERFLOW

public static final int TYPE_DATA_OVERFLOW

A data overflow page (the last page: + FLAG_LAST).

See Also:

Constant Field Values

TYPE_BTREE_LEAF

public static final int TYPE_BTREE_LEAF

A b-tree leaf page (without overflow: + FLAG_LAST).

See Also:

Constant Field Values

TYPE_BTREE_NODE

public static final int TYPE_BTREE_NODE

A b-tree node page (never has overflow pages).

See Also:

Constant Field Values

TYPE_FREE_LIST

public static final int TYPE_FREE_LIST

A page containing a list of free pages (the last page: + FLAG_LAST).

See Also:

Constant Field Values

TYPE_STREAM_TRUNK

public static final int TYPE_STREAM_TRUNK

A stream trunk page.

See Also:

Constant Field Values

TYPE_STREAM_DATA

public static final int TYPE_STREAM_DATA

A stream data page.

See Also:

Constant Field Values

changeCount

protected int changeCount

When this page was changed the last time.

Constructor Detail

Page

public Page()

Method Detail

moveTo

public abstract void moveTo(Session session,
          int newPos)

Copy the data to a new location, change the parent to point to the new location, and free up the current page.

Parameters:

session - the session

newPos - the new position

write

public abstract void write()

Write the page.

insert

public static <T> T[] insert(T[] old,
             int oldSize,
             int pos,
             T x)

Insert a value in an array. A new array is created if required.

Parameters:

old - the old array

oldSize - the old size

pos - the position

x - the value to insert

Returns:

the (new) array

remove

public static <T> T[] remove(T[] old,
             int oldSize,
             int pos)

Delete a value in an array. A new array is created if required.

Parameters:

old - the old array

oldSize - the old size

pos - the position

Returns:

the (new) array

insert

protected static long[] insert(long[] old,
            int oldSize,
            int pos,
            long x)

Insert a value in an array. A new array is created if required.

Parameters:

old - the old array

oldSize - the old size

pos - the position

x - the value to insert

Returns:

the (new) array

remove

protected static long[] remove(long[] old,
            int oldSize,
            int pos)

Delete a value in an array. A new array is created if required.

Parameters:

old - the old array

oldSize - the old size

pos - the position

Returns:

the (new) array

insert

protected static int[] insert(int[] old,
           int oldSize,
           int pos,
           int x)

Insert a value in an array. A new array is created if required.

Parameters:

old - the old array

oldSize - the old size

pos - the position

x - the value to insert

Returns:

the (new) array

remove

protected static int[] remove(int[] old,
           int oldSize,
           int pos)

Delete a value in an array. A new array is created if required.

Parameters:

old - the old array

oldSize - the old size

pos - the position

Returns:

the (new) array

add

protected static void add(int[] array,
       int from,
       int to,
       int x)

Add a value to a subset of the array.

Parameters:

array - the array

from - the index of the first element (including)

to - the index of the last element (excluding)

x - the value to add

canMove

public boolean canMove()

If this page can be moved. Transaction log and free-list pages can not.

Returns:

true if moving is allowed