org.h2.pagestore.db

Class PageDataNode

java.lang.Object

org.h2.util.CacheObject

org.h2.pagestore.Page

org.h2.pagestore.db.PageDataNode

All Implemented Interfaces:

java.lang.Comparable<CacheObject>

public class PageDataNode
extends Page

A leaf page that contains data of one or multiple rows. Format:

• page type: byte (0)
• checksum: short (1-2)
• parent page id (0 for root): int (3-6)
• table id: varInt
• count of all children (-1 if not known): int
• entry count: short
• rightmost child page id: int
• entries (child page id: int, key: varLong)

The key is the largest key of the respective child, meaning key[0] is the largest key of child[0].

Field Summary

Fields

Modifier and Type	Field and Description
protected Data	data The data page.
protected int	entryCount The number of entries.
protected PageDataIndex	index The index.
protected long[]	keys The row keys.
protected int	parentPageId The page number of the parent.
protected boolean	written Whether the data page is up-to-date.

Fields inherited from class org.h2.pagestore.Page

changeCount, FLAG_LAST, TYPE_BTREE_LEAF, TYPE_BTREE_NODE, TYPE_DATA_LEAF, TYPE_DATA_NODE, TYPE_DATA_OVERFLOW, TYPE_EMPTY, TYPE_FREE_LIST, TYPE_STREAM_DATA, TYPE_STREAM_TRUNK

Fields inherited from class org.h2.util.CacheObject

cacheChained, cacheNext, cachePrevious

Method Summary

Methods

Modifier and Type	Method and Description
boolean	canRemove() Check if the object can be removed from the cache.
int	getMemory() Get the estimated heap memory size.
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.
static Page	read(PageDataIndex index, Data data, int pageId) Read a data node page.
protected void	remapChildren(int old) Update the parent id of all children.
java.lang.String	toString()
void	write() Write the page.

Methods inherited from class org.h2.pagestore.Page

add, canMove, insert, insert, insert, remove, remove, remove

Methods inherited from class org.h2.util.CacheObject

compareTo, getPos, isChanged, isStream, setChanged, setPos

Methods inherited from class java.lang.Object

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

Field Detail

index

protected final PageDataIndex index

The index.

parentPageId

protected int parentPageId

The page number of the parent.

data

protected final Data data

The data page.

entryCount

protected int entryCount

The number of entries.

keys

protected long[] keys

The row keys.

written

protected boolean written

Whether the data page is up-to-date.

Method Detail

read

public static Page read(PageDataIndex index,
        Data data,
        int pageId)

Read a data node page.

Parameters:

index - the index

data - the data

pageId - the page id

Returns:

the page

remapChildren

protected void remapChildren(int old)

Update the parent id of all children.

Parameters:

old - the previous position

write

public void write()

Description copied from class: Page

Write the page.

Specified by:

write in class Page

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

moveTo

public void moveTo(Session session,
          int newPos)

Description copied from class: Page

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

Specified by:

moveTo in class Page

Parameters:

session - the session

newPos - the new position

getMemory

public int getMemory()

Get the estimated heap memory size.

Specified by:

getMemory in class CacheObject

Returns:

number of double words (4 bytes each)

canRemove

public boolean canRemove()

Description copied from class: CacheObject

Check if the object can be removed from the cache. For example pinned objects can not be removed.

Specified by:

canRemove in class CacheObject

Returns:

true if it can be removed