com.bigdata.btree

Interface IBTreeStatistics

All Known Implementing Classes:

AbstractBTree, BTree, BTreeStatistics, CommitRecordIndex, CommitTimeIndex, CounterSetBTree, EventReceiver.EventBTree, IndexSegment, IndexSegmentIndex, JournalIndex, MetadataIndex, Name2Addr, TestMROWTransactions.MyBTree, TestRestartSafe.MyBTree, TxId2CommitTimeIndex

public interface IBTreeStatistics

Interface used to report out some statistics about a B+Tree. These statistics may be used in combination with a disk cost model to predict the cost (latency) associated with a variety of operations on the B+Tree. All values reported by this interface are tracked explicitly by the AbstractBTree and do not require DISK IO.

Version:

$Id$

Author:

Bryan Thompson

Method Summary

Methods

Modifier and Type	Method and Description
int	getBranchingFactor() The branching factor for the btree.
long	getEntryCount() The #of entries (aka tuples) in the AbstractBTree.
int	getHeight() The height of the btree.
long	getLeafCount() The #of leaf nodes in the AbstractBTree.
long	getNodeCount() The #of non-leaf nodes in the AbstractBTree.
IBTreeUtilizationReport	getUtilization() Computes and returns the utilization of the tree.

Method Detail

getBranchingFactor

int getBranchingFactor()

The branching factor for the btree.

getHeight

int getHeight()

The height of the btree. The height is the #of levels minus one. A btree with only a root leaf has height := 0. A btree with a root node and one level of leaves under it has height := 1. Note that all leaves of a btree are at the same height (this is what is means for the btree to be "balanced"). Also note that the height only changes when we split or join the root node (a btree maintains balance by growing and shrinking in levels from the top rather than the leaves).

getNodeCount

long getNodeCount()

The #of non-leaf nodes in the AbstractBTree. This is zero (0) for a new btree.

getLeafCount

long getLeafCount()

The #of leaf nodes in the AbstractBTree. This is one (1) for a new btree.

getEntryCount

long getEntryCount()

The #of entries (aka tuples) in the AbstractBTree. This is zero (0) for a new B+Tree. When the B+Tree supports delete markers, this value also includes tuples which have been marked as deleted.

getUtilization

IBTreeUtilizationReport getUtilization()

Computes and returns the utilization of the tree. The utilization figures do not factor in the space requirements of nodes and leaves.