Package org.apache.cayenne.dba

Class JdbcPkGenerator

java.lang.Object
org.apache.cayenne.dba.JdbcPkGenerator
All Implemented Interfaces:
PkGenerator
Direct Known Subclasses:
FrontBasePkGenerator, MySQLPkGenerator, OpenBasePkGenerator, OraclePkGenerator, SybasePkGenerator
public class JdbcPkGenerator extends Object implements PkGenerator
Default primary key generator implementation. Uses a lookup table named "AUTO_PK_SUPPORT" to search and increment primary keys for tables.

  • Field Details

  • Constructor Details

    • JdbcPkGenerator

      public JdbcPkGenerator()
      Since:
      4.1

    • JdbcPkGenerator

      public JdbcPkGenerator(JdbcAdapter adapter)

  • Method Details

    • getAdapter

      public JdbcAdapter getAdapter()
      Description copied from interface: PkGenerator
      Get an adapter associated with current PkGenerator
      Specified by:
      getAdapter in interface PkGenerator

    • createAutoPk

      public void createAutoPk(DataNode node, List<DbEntity> dbEntities) throws Exception
      Description copied from interface: PkGenerator
      Generates necessary database objects to provide automatic primary key support.
      Specified by:
      createAutoPk in interface PkGenerator
      Parameters:
      node - node that provides access to a DataSource.
      dbEntities - a list of entities that require primary key auto-generation support
      Throws:
      Exception

    • createAutoPkStatements

      public List<String> createAutoPkStatements(List<DbEntity> dbEntities)
      Description copied from interface: PkGenerator
      Returns a list of SQL strings needed to generates database objects to provide automatic primary support for the list of entities. No actual database operations are performed.
      Specified by:
      createAutoPkStatements in interface PkGenerator

    • dropAutoPk

      public void dropAutoPk(DataNode node, List<DbEntity> dbEntities) throws Exception
      Drops table named "AUTO_PK_SUPPORT" if it exists in the database.
      Specified by:
      dropAutoPk in interface PkGenerator
      Parameters:
      node - node that provides access to a DataSource.
      dbEntities - a list of entities whose primary key auto-generation support should be dropped.
      Throws:
      Exception

    • dropAutoPkStatements

      public List<String> dropAutoPkStatements(List<DbEntity> dbEntities)
      Description copied from interface: PkGenerator
      Returns SQL string needed to drop database objects associated with automatic primary key generation. No actual database operations are performed.
      Specified by:
      dropAutoPkStatements in interface PkGenerator

    • pkTableCreateString

      protected String pkTableCreateString()

    • pkDeleteString

      protected String pkDeleteString(List<DbEntity> dbEntities)

    • pkCreateString

      protected String pkCreateString(String entName)

    • pkSelectString

      protected String pkSelectString(String entName)

    • pkUpdateString

      protected String pkUpdateString(String entName)

    • dropAutoPkString

      protected String dropAutoPkString()

    • autoPkTableExists

      protected boolean autoPkTableExists(DataNode node) throws SQLException
      Checks if AUTO_PK_TABLE already exists in the database.
      Throws:
      SQLException

    • runUpdate

      public int runUpdate(DataNode node, String sql) throws SQLException
      Runs JDBC update over a Connection obtained from DataNode. Returns a number of objects returned from update.
      Throws:
      SQLException - in case of query failure.

    • generatePk

      public Object generatePk(DataNode node, DbAttribute pk) throws Exception
      Generates a unique and non-repeating primary key for specified dbEntity.

      This implementation is naive since it does not lock the database rows when executing select and subsequent update. Adapter-specific implementations are more robust.

      Specified by:
      generatePk in interface PkGenerator
      Throws:
      Exception
      Since:
      3.0

    • setAdapter

      public void setAdapter(DbAdapter adapter)
      Description copied from interface: PkGenerator
      Install the adapter associated with current PkGenerator
      Specified by:
      setAdapter in interface PkGenerator

    • longPkFromDatabase

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

      Throws:
      Exception
      Since:
      3.0

    • getPkCacheSize

      public int getPkCacheSize()
      Returns a size of the entity primary key cache. Default value is 20. If cache size is set to a value less or equals than "one", no primary key caching is done.

    • setPkCacheSize

      public void setPkCacheSize(int pkCacheSize)
      Sets the size of the entity primary key cache. If pkCacheSize parameter is less than 1, cache size is set to "one".

      Note that our tests show that setting primary key cache value to anything much bigger than 20 does not give any significant performance increase. Therefore it does not make sense to use bigger values, since this may potentially create big gaps in the database primary key sequences in cases like application crashes or restarts.

    • reset

      public void reset()
      Description copied from interface: PkGenerator
      Resets any cached primary keys forcing generator to go to the database next time id generation is requested. May not be applicable for all generator implementations.
      Specified by:
      reset in interface PkGenerator