org.springframework.jdbc.support.incrementer

Class MySQLMaxValueIncrementer

java.lang.Object

org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer

org.springframework.jdbc.support.incrementer.AbstractColumnMaxValueIncrementer

org.springframework.jdbc.support.incrementer.MySQLMaxValueIncrementer

All Implemented Interfaces:

InitializingBean, DataFieldMaxValueIncrementer

public class MySQLMaxValueIncrementer
extends AbstractColumnMaxValueIncrementer

DataFieldMaxValueIncrementer that increments the maximum value of a given MySQL table with the equivalent of an auto-increment column. Note: If you use this class, your MySQL key column should NOT be auto-increment, 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. The table type of the sequence table should be MyISAM so the sequences are allocated without regard to any transactions that might be in progress.

Example:

create table tab (id int unsigned not null primary key, text varchar(100));
 create table tab_sequence (value int not null) type=MYISAM;
 insert into tab_sequence values(0);

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.

Author:

Jean-Pierre Pawlak, Thomas Risberg, Juergen Hoeller

Field Summary

Fields

Modifier and Type	Field and Description
private long	maxId The max id to serve
private long	nextId The next id to serve
private static java.lang.String	VALUE_SQL The SQL string for retrieving the new sequence value

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

paddingLength

Constructor Summary

Constructors

Constructor and Description
MySQLMaxValueIncrementer() Default constructor for bean property style usage.
MySQLMaxValueIncrementer(javax.sql.DataSource dataSource, java.lang.String incrementerName, java.lang.String columnName) Convenience constructor.

Method Summary

Modifier and Type	Method and Description
protected long	getNextKey() Determine the next key to use, as a long.

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

Field Detail

VALUE_SQL

private static final java.lang.String VALUE_SQL

The SQL string for retrieving the new sequence value

See Also:

Constant Field Values

nextId

private long nextId

The next id to serve

maxId

private long maxId

The max id to serve

Constructor Detail

MySQLMaxValueIncrementer

public MySQLMaxValueIncrementer()

Default constructor for bean property style usage.

See Also:

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

MySQLMaxValueIncrementer

public MySQLMaxValueIncrementer(javax.sql.DataSource dataSource,
                                java.lang.String incrementerName,
                                java.lang.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

Method Detail

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