Spring Framework 6.1.4 · org.springframework.jdbc.support.incrementer.MySQLMaxValueIncrementer

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 storage engine used by the sequence table can be MYISAM or INNODB since the sequences are allocated using a separate connection without being affected by any other 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);
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.

It is possible to avoid acquiring a new connection for the incrementer by setting the "useNewConnection" property to false. In this case you MUST use a non-transactional storage engine like MYISAM when defining the incrementer table.

As of Spring Framework 5.3.7, MySQLMaxValueIncrementer is compatible with MySQL safe updates mode.

Field Summary

Modifier and Type	Field and Description
private long	maxId The max id to serve.
private long	nextId The next id to serve.
private boolean	useNewConnection Whether to use a new connection for the incrementer.
private static final String	VALUE_SQL The SQL string for retrieving the new sequence value.

Constructor Summary

Access	Constructor and Description
public	MySQLMaxValueIncrementer() Default constructor for bean property style usage.
public	MySQLMaxValueIncrementer(DataSource the DataSource to use dataSource, String the name of the sequence table to use incrementerName, String the name of the column in the sequence table to use columnName) Convenience constructor.

Method Summary

Modifier and Type	Method and Description
protected synchronized long	getNextKey() Implements abstract org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer.getNextKey. Determine the next key to use, as a long.
public void	setUseNewConnection(boolean useNewConnection) Set whether to use a new connection for the incrementer.

Inherited from org.springframework.jdbc.support.incrementer.AbstractColumnMaxValueIncrementer:: afterPropertiesSet getCacheSize getColumnName setCacheSize setColumnName

Field Detail

maxId	back to summary
private long maxId The max id to serve.

nextId	back to summary
private long nextId The next id to serve.

useNewConnection	back to summary
private boolean useNewConnection Whether to use a new connection for the incrementer.

VALUE_SQL	back to summary
private static final String VALUE_SQL The SQL string for retrieving the new sequence value.

Constructor Detail

MySQLMaxValueIncrementer back to summary

MySQLMaxValueIncrementer	back to summary
public MySQLMaxValueIncrementer() Default constructor for bean property style usage. See Also `setDataSource`, `setIncrementerName`, `setColumnName`

public MySQLMaxValueIncrementer()

Default constructor for bean property style usage.

See Also: setDataSource, setIncrementerName, setColumnName

MySQLMaxValueIncrementer	back to summary
public MySQLMaxValueIncrementer(DataSource dataSource, String incrementerName, String columnName) Convenience constructor. Parameters dataSource:DataSource the DataSource to use incrementerName:String the name of the sequence table to use columnName:String the name of the column in the sequence table to use

MySQLMaxValueIncrementer

back to summary

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

Convenience constructor.

Parameters

dataSource:DataSource: the DataSource to use
incrementerName:String: the name of the sequence table to use
columnName:String: the name of the column in the sequence table to use

Method Detail

getNextKey	back to summary
protected synchronized long getNextKey() throws DataAccessException Implements abstract org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer.getNextKey. Doc from org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer.getNextKey. Determine the next key to use, as a long. Returns:long the key to use as a long. It will eventually be converted later in another format by the public concrete methods of this class. Annotations @Override

getNextKey

back to summary

protected synchronized long getNextKey() throws DataAccessException

Implements abstract org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer.getNextKey.

Doc from org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer.getNextKey.

Determine the next key to use, as a long.

Returns:long

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

Annotations

@Override

setUseNewConnection back to summary

setUseNewConnection	back to summary
public void setUseNewConnection(boolean useNewConnection) Set whether to use a new connection for the incrementer. `true` is necessary to support transactional storage engines, using an isolated separate transaction for the increment operation. `false` is sufficient if the storage engine of the sequence table is non-transactional (like MYISAM), avoiding the effort of acquiring an extra `Connection` for the increment operation. Default is `true` since Spring Framework 5.0. Since 4.3.6 See Also `DataSource#getConnection()`

public void setUseNewConnection(boolean useNewConnection)

Set whether to use a new connection for the incrementer.

true is necessary to support transactional storage engines, using an isolated separate transaction for the increment operation. false is sufficient if the storage engine of the sequence table is non-transactional (like MYISAM), avoiding the effort of acquiring an extra Connection for the increment operation.

Default is true since Spring Framework 5.0.

Since: 4.3.6
See Also: DataSource#getConnection()