DerbyMaxValueIncrementer

Class Overview

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!

Summary

[Expand] Inherited Fields
From class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer protected int paddingLength The length to which a string result should be pre-pended with zeroes

Public Constructors
	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.

Public Methods
String	getDummyName() Return the name of the dummy column.
void	setDummyName(String dummyName) Set the name of the dummy column.

Protected Methods
synchronized long	getNextKey() Determine the next key to use, as a long.

[Expand] Inherited Methods
From class org.springframework.jdbc.support.incrementer.AbstractColumnMaxValueIncrementer 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. void setCacheSize(int cacheSize) Set the number of buffered keys. void setColumnName(String columnName) Set the name of the column in the sequence table.
From class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer void afterPropertiesSet() Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware). DataSource getDataSource() Return the data source to retrieve the value from. String getIncrementerName() Return the name of the sequence/table. abstract long getNextKey() Determine the next key to use, as a long. int getPaddingLength() Return the padding length for String values. int nextIntValue() Increment the data store field's max value as int. long nextLongValue() Increment the data store field's max value as long. String nextStringValue() Increment the data store field's max value as String. void setDataSource(DataSource dataSource) Set the data source to retrieve the value from. void setIncrementerName(String incrementerName) Set the name of the sequence/table. void setPaddingLength(int paddingLength) Set the padding length, i.e.
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait() final void wait(long arg0, int arg1) final void wait(long arg0)
From interface org.springframework.beans.factory.InitializingBean abstract void afterPropertiesSet() Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).
From interface org.springframework.jdbc.support.incrementer.DataFieldMaxValueIncrementer abstract int nextIntValue() Increment the data store field's max value as int. abstract long nextLongValue() Increment the data store field's max value as long. abstract String nextStringValue() Increment the data store field's max value as String.