OptimizerFactory.HiLoOptimizer

Class Overview

Optimizer which applies a 'hilo' algorithm in memory to achieve optimization.

A 'hilo' algorithm is simply a means for a single value stored in the database to represent a "bucket" of possible, contiguous values. The database value identifies which particular bucket we are on.

This database value must be paired with another value that defines the size of the bucket; the number of possible values available. The incrementSize serves this purpose. The naming here is meant more for consistency in that this value serves the same purpose as the increment supplied to the OptimizerFactory.PooledOptimizer.

The general algorithms used to determine the bucket are:

1. upperLimit = (databaseValue * incrementSize) + 1
2. lowerLimit = upperLimit - 1

As an example, consider a case with incrementSize of 10. Initially the database holds 1:

1. upperLimit = (1 * 20) + 1 = 21
2. lowerLimit = 21 - 20 = 1

From there we increment the value from lowerLimit until we reach the upperLimit, at which point we would define a new bucket. The database now contains 2, though incrementSize remains unchanged:

1. upperLimit = (2 * 20) + 1 = 41
2. lowerLimit = 41 - 20 = 21

And so on...

Note, 'value' always (after init) holds the next value to return

Summary

[Expand] Inherited Fields
From class org.hibernate.id.enhanced.OptimizerFactory.OptimizerSupport protected final int incrementSize protected final Class returnClass

Public Constructors
	OptimizerFactory.HiLoOptimizer(Class returnClass, int incrementSize)

Public Methods
boolean	applyIncrementSizeToSourceValues()
synchronized Serializable	generate(AccessCallback callback)
IntegralDataTypeHolder	getHiValue() Getter for property 'upperLimit'.
IntegralDataTypeHolder	getLastSourceValue()
IntegralDataTypeHolder	getLastValue() Getter for property 'lastValue'.

[Expand] Inherited Methods
From class org.hibernate.id.enhanced.OptimizerFactory.OptimizerSupport final int getIncrementSize() Retrieves the defined increment size. final Class getReturnClass() Getter for property 'returnClass'.
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait() final void wait(long arg0, int arg1) final void wait(long arg0)
From interface org.hibernate.id.enhanced.Optimizer abstract boolean applyIncrementSizeToSourceValues() Are increments to be applied to the values stored in the underlying value source? abstract Serializable generate(AccessCallback callback) Generate an identifier value accounting for this specific optimization. abstract int getIncrementSize() Retrieves the defined increment size. abstract IntegralDataTypeHolder getLastSourceValue() A common means to access the last value obtained from the underlying source.