org.apache.cayenne.dba.derby

## Class DerbyPkGenerator

- java.lang.Object
- - org.apache.cayenne.dba.JdbcPkGenerator
  - - org.apache.cayenne.dba.derby.DerbyPkGenerator

- All Implemented Interfaces:
    PkGenerator

      public class DerbyPkGenerator
      extends JdbcPkGenerator

  Default PK generator for Derby that uses updateable ResultSet to get the next id from the lookup table.
  Since:
    1.2

- - ### Field Summary

    - ### Fields inherited from class org.apache.cayenne.dba.JdbcPkGenerator

      `adapter, DEFAULT_PK_CACHE_SIZE, pkCache, pkCacheSize, pkStartValue`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected long` | `longPkFromDatabase(DataNode node, DbEntity entity)` Performs primary key generation ignoring cache.

    - ### Methods inherited from class org.apache.cayenne.dba.JdbcPkGenerator

      `autoPkTableExists, createAutoPk, createAutoPkStatements, dropAutoPk, dropAutoPkStatements, dropAutoPkString, generatePk, getAdapter, getPkCacheSize, pkCreateString, pkDeleteString, pkSelectString, pkTableCreateString, pkUpdateString, reset, runUpdate, setPkCacheSize`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Method Detail

    - #### longPkFromDatabase

          protected long longPkFromDatabase(DataNode node,
                                            DbEntity entity)
                                     throws Exception

      Description copied from class: `JdbcPkGenerator`
      Performs primary key generation ignoring cache. Generates a range of primary keys as specified by "pkCacheSize" bean property.

      This method is called internally from "generatePkForDbEntity" and then generated range of key values is saved in cache for performance. Subclasses that implement different primary key generation solutions should override this method, not "generatePkForDbEntity".

      Overrides:
        `longPkFromDatabase` in class `JdbcPkGenerator`
      Throws:
        `Exception`
      Since:
        3.0

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