org.h2.index
Class BtreeHead

java.lang.Object
  extended by org.h2.util.CacheObject
      extended by org.h2.store.Record
          extended by org.h2.index.BtreeHead

public class BtreeHead
extends Record

The head page of a b-tree index. There is exactly one head page for each such index, and it contains meta data such as the location of the root page. Unlike the root page of a b-tree index, the head page always stays at the same place.


Field Summary
 
Fields inherited from class org.h2.util.CacheObject
blockCount, cacheQueue, chained, next, previous
 
Constructor Summary
BtreeHead()
           
BtreeHead(DataPage s)
           
 
Method Summary
 int getByteCount(DataPage dummy)
          Get the number of bytes required for the data if the given data page would be used.
 boolean isPinned()
          Check if this cache object can be removed from the cache.
 void write(DataPage buff)
          Write the record to the data page.
 
Methods inherited from class org.h2.store.Record
canRemove, commit, getSessionId, getStorageId, isDeleted, isEmpty, isLogWritten, prepareWrite, setDeleted, setLastLog, setLogWritten, setSessionId, setStorageId
 
Methods inherited from class org.h2.util.CacheObject
getBlockCount, getMemorySize, getPos, isChanged, setBlockCount, setChanged, setPos, sort
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

BtreeHead

public BtreeHead()

BtreeHead

public BtreeHead(DataPage s)
Method Detail

getByteCount

public int getByteCount(DataPage dummy)
Description copied from class: Record
Get the number of bytes required for the data if the given data page would be used.

Specified by:
getByteCount in class Record
Parameters:
dummy - the template data page
Returns:
the number of bytes

write

public void write(DataPage buff)
Description copied from class: Record
Write the record to the data page.

Specified by:
write in class Record
Parameters:
buff - the data page

isPinned

public boolean isPinned()
Description copied from class: CacheObject
Check if this cache object can be removed from the cache.

Overrides:
isPinned in class CacheObject
Returns:
if it can be removed