org.springframework.jdbc.support.incrementer
Class DerbyMaxValueIncrementer

java.lang.Object
  org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer
      org.springframework.jdbc.support.incrementer.DerbyMaxValueIncrementer

All Implemented Interfaces:

InitializingBean, DataFieldMaxValueIncrementer

public class DerbyMaxValueIncrementer
extends AbstractDataFieldMaxValueIncrementer

Class to increment maximum value of a given Derby table with the equivalent of an auto-increment column. Note: If you use this class, your Derby key column should NOT be defined as an IDENTITY column, as the sequence table does the job. Thanks to Endre Stolsvik for the suggestion!

The sequence is kept in a table. There should be one sequence table per table that needs an auto-generated key.

Derby requires an additional column to be used for the insert since it is impossible to insert a null into the identity column and have the value generated. This is solved by providing the name of a dummy column that also must be created in the sequence table.

Example:

create table tab (id int not null primary key, text varchar(100));
 create table tab_sequence (value int generated always as identity, dummy char(1));
 insert into tab_sequence (dummy) values(null);

If cacheSize is set, the intermediate values are served without querying the database. If the server or your application is stopped or crashes or a transaction is rolled back, the unused values will never be served. The maximum hole size in numbering is consequently the value of cacheSize. HINT: Since Derby supports the JDBC 3.0 method getGeneratedKeys it's recommended to use IDENTITY columns directly in the tables and then utilizing a KeyHolder when calling the with the update(PreparedStatementCreator psc, KeyHolder generatedKeyHolder) method of the JdbcTemplate.

Since:

2.5

Author:

Thomas Risberg

Field Summary

Fields inherited from class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer

paddingLength

Constructor Summary

DerbyMaxValueIncrementer()
Default constructor.

DerbyMaxValueIncrementer(DataSource ds, String incrementerName, String columnName)
Convenience constructor.

DerbyMaxValueIncrementer(DataSource ds, String incrementerName, String columnName, String dummyName)
Convenience constructor.

Method Summary

void	afterPropertiesSet() Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).
int	getCacheSize() Return the number of buffered keys.
String	getColumnName() Return the name of the column in the sequence table.
String	getDummyName() Return the name of the dummy column.
protected long	getNextKey() Determine the next key to use, as a long.
void	setCacheSize(int cacheSize) Set the number of buffered keys.
void	setColumnName(String columnName) Set the name of the column in the sequence table.
void	setDummyName(String dummyName) Set the name of the dummy column.

Methods inherited from class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer

getDataSource, getIncrementerName, getPaddingLength, nextIntValue, nextLongValue, nextStringValue, setDataSource, setIncrementerName, setPaddingLength

Methods inherited from class java.lang.Object

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

Constructor Detail

DerbyMaxValueIncrementer

public DerbyMaxValueIncrementer()

Default constructor.

DerbyMaxValueIncrementer

public DerbyMaxValueIncrementer(DataSource ds,
                                String incrementerName,
                                String columnName)

Convenience constructor.

Parameters:

ds - the DataSource to use

incrementerName - the name of the sequence/table to use

columnName - the name of the column in the sequence table to use

DerbyMaxValueIncrementer

public DerbyMaxValueIncrementer(DataSource ds,
                                String incrementerName,
                                String columnName,
                                String dummyName)

Convenience constructor.

Parameters:

ds - the DataSource to use

incrementerName - the name of the sequence/table to use

columnName - the name of the column in the sequence table to use

dummyName - the name of the dummy column used for inserts

Method Detail

setColumnName

public void setColumnName(String columnName)

Set the name of the column in the sequence table.

getColumnName

public String getColumnName()

Return the name of the column in the sequence table.

setDummyName

public void setDummyName(String dummyName)

Set the name of the dummy column.

getDummyName

public String getDummyName()

Return the name of the dummy column.

setCacheSize

public void setCacheSize(int cacheSize)

Set the number of buffered keys.

getCacheSize

public int getCacheSize()

Return the number of buffered keys.

afterPropertiesSet

public void afterPropertiesSet()

Description copied from interface: InitializingBean

Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).

This method allows the bean instance to perform initialization only possible when all bean properties have been set and to throw an exception in the event of misconfiguration.

Specified by:

afterPropertiesSet in interface InitializingBean

Overrides:

afterPropertiesSet in class AbstractDataFieldMaxValueIncrementer

getNextKey

protected long getNextKey()
                   throws DataAccessException

Description copied from class: AbstractDataFieldMaxValueIncrementer

Determine the next key to use, as a long.

Specified by:

getNextKey in class AbstractDataFieldMaxValueIncrementer

Returns:

the key to use as a long. It will eventually be converted later in another format by the public concrete methods of this class.

Throws:

DataAccessException