public class DerbyMaxValueIncrementer extends AbstractIdentityColumnMaxValueIncrementer
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!
paddingLength| Constructor and Description |
|---|
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.
|
| Modifier and Type | Method and Description |
|---|---|
String |
getDummyName()
Return the name of the dummy column.
|
protected String |
getIdentityStatement()
Statement to use to obtain the current identity value.
|
protected String |
getIncrementStatement()
Statement to use to increment the "sequence" value.
|
void |
setDummyName(String dummyName)
Set the name of the dummy column.
|
getDeleteStatement, getNextKey, isDeleteSpecificValues, setDeleteSpecificValuesafterPropertiesSet, getCacheSize, getColumnName, setCacheSize, setColumnNamegetDataSource, getIncrementerName, getPaddingLength, nextIntValue, nextLongValue, nextStringValue, setDataSource, setIncrementerName, setPaddingLengthpublic DerbyMaxValueIncrementer()
public DerbyMaxValueIncrementer(DataSource dataSource, String incrementerName, 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 usepublic DerbyMaxValueIncrementer(DataSource dataSource, String incrementerName, String columnName, String dummyName)
dataSource - the DataSource to useincrementerName - the name of the sequence/table to usecolumnName - the name of the column in the sequence table to usedummyName - the name of the dummy column used for insertspublic void setDummyName(String dummyName)
public String getDummyName()
protected String getIncrementStatement()
AbstractIdentityColumnMaxValueIncrementergetIncrementStatement in class AbstractIdentityColumnMaxValueIncrementerprotected String getIdentityStatement()
AbstractIdentityColumnMaxValueIncrementergetIdentityStatement in class AbstractIdentityColumnMaxValueIncrementer