org.springframework.jdbc.support.incrementer
Class DerbyMaxValueIncrementer

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

All Implemented Interfaces:

InitializingBean, DataFieldMaxValueIncrementer

public class DerbyMaxValueIncrementer
extends AbstractColumnMaxValueIncrementer

DataFieldMaxValueIncrementer that increments the 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.

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 getGeneratedKeys method, it is 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.

Thanks to Endre Stolsvik for the suggestion!

Since:

2.5

Author:

Thomas Risberg, Juergen Hoeller

Field Summary

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

paddingLength

Constructor Summary

DerbyMaxValueIncrementer()
Default constructor for bean property style usage.

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

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

Method Summary

String	getDummyName() Return the name of the dummy column.
protected long	getNextKey() Determine the next key to use, as a long.
void	setDummyName(String dummyName) Set the name of the dummy column.

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

afterPropertiesSet, getCacheSize, getColumnName, setCacheSize, setColumnName

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 for bean property style usage.

See Also:

AbstractDataFieldMaxValueIncrementer.setDataSource(javax.sql.DataSource), AbstractDataFieldMaxValueIncrementer.setIncrementerName(java.lang.String), AbstractColumnMaxValueIncrementer.setColumnName(java.lang.String)

DerbyMaxValueIncrementer

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

Convenience constructor.

Parameters:

dataSource - 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 dataSource,
                                String incrementerName,
                                String columnName,
                                String dummyName)

Convenience constructor.

Parameters:

dataSource - 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

setDummyName

public void setDummyName(String dummyName)

Set the name of the dummy column.

getDummyName

public String getDummyName()

Return the name of the dummy column.

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