org.datanucleus.store.rdbms.valuegenerator
Class MaxGenerator

java.lang.Object
  extended by org.datanucleus.store.valuegenerator.AbstractGenerator
      extended by org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator
          extended by org.datanucleus.store.rdbms.valuegenerator.AbstractRDBMSGenerator
              extended by 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. MaxPoidGenerator works with numbers, so clients using this generator must cast the ID to Long *

Required user properties

Optional user properties


Field Summary
protected static org.datanucleus.util.Localiser LOCALISER_RDBMS
           
 
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, LOCALISER, name, properties, repositoryExists
 
Constructor Summary
MaxGenerator(java.lang.String name, java.util.Properties props)
          Constructor.
 
Method Summary
 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
 

Field Detail

LOCALISER_RDBMS

protected static final org.datanucleus.util.Localiser LOCALISER_RDBMS
Constructor Detail

MaxGenerator

public MaxGenerator(java.lang.String name,
                    java.util.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


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