org.exolab.castor.jdo.keygen
Class MaxKeyGeneratorFactory

java.lang.Object
  extended by org.exolab.castor.jdo.keygen.MaxKeyGeneratorFactory
All Implemented Interfaces:
KeyGeneratorFactory

public final class MaxKeyGeneratorFactory
extends java.lang.Object
implements KeyGeneratorFactory

MAX key generator factory. The short name of this key generator is "MAX". It uses the following alrorithm: the maximum value of the primary key is fetched and the correspondent record is locked until the end of transaction, generator returns (max + 1). The lock guarantees that key generators of concurrent transactions will not use this key value, so DuplicateKeyException is impossible. If the table is empty, generator returns 1, no lock is put, DuplicateKeyException is possible.

Version:
$Revision: 1.1 $ $Date: 2005/06/01 12:08:16 $
Author:
Oleg Nitz
See Also:
MaxKeyGenerator

Constructor Summary
MaxKeyGeneratorFactory()
           
 
Method Summary
 KeyGenerator getKeyGenerator(PersistenceFactory factory, java.util.Properties params, int sqlType)
          Produce the key generator.
 java.lang.String getName()
          The short name of this key generator is "MAX"
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MaxKeyGeneratorFactory

public MaxKeyGeneratorFactory()
Method Detail

getKeyGenerator

public KeyGenerator getKeyGenerator(PersistenceFactory factory,
                                    java.util.Properties params,
                                    int sqlType)
                             throws MappingException
Produce the key generator.

Specified by:
getKeyGenerator in interface KeyGeneratorFactory
Parameters:
factory - Helper object for obtaining database-specific QuerySyntax.
params - Parameters for key generator.
sqlType - The SQL type of the primary key, the generated identities must have the corresponding Java type, e.g. java.sql.Types.INTEGER corresponds to java.lang.Integer, java.sql.Types.NUMERIC corresponds to java.lang.BigDecimal.
Throws:
MappingException
Factory:
Helper object for obtaining database-specific QuerySyntax.

getName

public java.lang.String getName()
The short name of this key generator is "MAX"

Specified by:
getName in interface KeyGeneratorFactory


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