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java.lang.Objectorg.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer
org.springframework.jdbc.support.incrementer.AbstractColumnMaxValueIncrementer
org.springframework.jdbc.support.incrementer.MySQLMaxValueIncrementer
public class 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 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.
Field Summary | |
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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 |
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paddingLength |
Constructor Summary | |
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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 | |
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protected long |
getNextKey()
Determine the next key to use, as a long. |
Methods inherited from class org.springframework.jdbc.support.incrementer.AbstractColumnMaxValueIncrementer |
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afterPropertiesSet, getCacheSize, getColumnName, setCacheSize, setColumnName |
Methods inherited from class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer |
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getDataSource, getIncrementerName, getPaddingLength, nextIntValue, nextLongValue, nextStringValue, setDataSource, setIncrementerName, setPaddingLength |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private static final java.lang.String VALUE_SQL
private long nextId
private long maxId
Constructor Detail |
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public MySQLMaxValueIncrementer()
AbstractDataFieldMaxValueIncrementer.setDataSource(javax.sql.DataSource)
,
AbstractDataFieldMaxValueIncrementer.setIncrementerName(java.lang.String)
,
AbstractColumnMaxValueIncrementer.setColumnName(java.lang.String)
public MySQLMaxValueIncrementer(javax.sql.DataSource dataSource, java.lang.String incrementerName, java.lang.String columnName)
dataSource
- the DataSource to useincrementerName
- the name of the sequence/table to usecolumnName
- the name of the column in the sequence table to useMethod Detail |
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protected long getNextKey() throws DataAccessException
AbstractDataFieldMaxValueIncrementer
getNextKey
in class AbstractDataFieldMaxValueIncrementer
DataAccessException
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