org.datanucleus.store.rdbms.valuegenerator

Class MaxGenerator

java.lang.Object

org.datanucleus.store.valuegenerator.AbstractGenerator<T>

org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator<T>

org.datanucleus.store.rdbms.valuegenerator.AbstractRDBMSGenerator

org.datanucleus.store.rdbms.valuegenerator.MaxGenerator

All Implemented Interfaces:

org.datanucleus.store.valuegenerator.ValueGenerator

public class MaxGenerator
extends AbstractRDBMSGenerator

This generator for Relational Databases uses the "select max(column) from table" strategy. The block size is limited to 1. MaxGenerator works with numbers, so clients using this generator must cast the ID to Long.

Nested Class Summary

Nested classes/interfaces inherited from class org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator

org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator.ConnectionPreference

Field Summary

Fields inherited from class org.datanucleus.store.rdbms.valuegenerator.AbstractRDBMSGenerator

connection

Fields inherited from class org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator

connectionProvider, storeMgr

Fields inherited from class org.datanucleus.store.valuegenerator.AbstractGenerator

allocationSize, block, initialValue, name, properties, repositoryExists

Constructor Summary

Constructors

Constructor and Description
MaxGenerator(String name, Properties props) Constructor.

Method Summary

Modifier and Type	Method and Description
org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator.ConnectionPreference	getConnectionPreference()
org.datanucleus.store.valuegenerator.ValueGenerationBlock	reserveBlock(long size) Method to reserve a block of identities.

Methods inherited from class org.datanucleus.store.rdbms.valuegenerator.AbstractRDBMSGenerator

obtainGenerationBlock, requiresConnection

Methods inherited from class org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator

setConnectionProvider, setStoreManager

Methods inherited from class org.datanucleus.store.valuegenerator.AbstractGenerator

allocate, createRepository, current, currentValue, getName, getStorageClass, next, nextValue, obtainGenerationBlock, repositoryExists, requiresRepository, reserveBlock

Methods inherited from class java.lang.Object

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

Constructor Detail

MaxGenerator

public MaxGenerator(String name,
                    Properties props)

Constructor.

Parameters:

name - Symbolic name for this generator

props - Properties defining the behaviour of this generator

Method Detail

reserveBlock

public org.datanucleus.store.valuegenerator.ValueGenerationBlock reserveBlock(long size)

Method to reserve a block of identities. Note : Only allocates a single id always.

Specified by:

reserveBlock in class org.datanucleus.store.valuegenerator.AbstractGenerator

Parameters:

size - The block size

Returns:

The reserved block

getConnectionPreference

public org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator.ConnectionPreference getConnectionPreference()

Overrides:

getConnectionPreference in class org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator