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 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.
- Author:
- Jean-Pierre Pawlak, Thomas Risberg, Juergen Hoeller
Field Summary
Fields inherited from class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer
paddingLength
Constructor Summary
Constructors Constructor Description MySQLMaxValueIncrementer()
Default constructor for bean property style usage.MySQLMaxValueIncrementer(DataSource dataSource, String incrementerName, String columnName)
Convenience constructor.
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected long
getNextKey()
Determine the next key to use, as a long.void
setUseNewConnection(boolean useNewConnection)
Set whether to use a new connection for the incrementer.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
Constructor Detail
MySQLMaxValueIncrementer
public MySQLMaxValueIncrementer()
Default constructor for bean property style usage.
MySQLMaxValueIncrementer
public MySQLMaxValueIncrementer(DataSource dataSource, String incrementerName, String columnName)
Convenience constructor.- Parameters:
dataSource
- the DataSource to useincrementerName
- the name of the sequence table to usecolumnName
- the name of the column in the sequence table to use
Method Detail
setUseNewConnection
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 extraConnection
for the increment operation.Default is
false
in the Spring Framework 4.3.x line.- Since:
- 4.3.6
- See Also:
DataSource.getConnection()
getNextKey
protected long getNextKey() throws DataAccessException
Description copied from class:AbstractDataFieldMaxValueIncrementer
Determine the next key to use, as a long.- Specified by:
getNextKey
in classAbstractDataFieldMaxValueIncrementer
- 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