Class SequencePkGenerator

java.lang.Object
org.apache.cayenne.dba.JdbcPkGenerator
org.apache.cayenne.dba.SequencePkGenerator
All Implemented Interfaces:
PkGenerator
Direct Known Subclasses:
DB2PkGenerator, DerbyPkGenerator, H2PkGenerator, IngresPkGenerator, OraclePkGenerator, PostgresPkGenerator
public abstract class SequencePkGenerator extends JdbcPkGenerator
A common superclass for sequence-based primary key generators. Uses database sequences to generate primary key values, which is generally faster than the lookup table approach implemented by JdbcPkGenerator. Concrete subclasses provide database-specific SQL for selecting the next sequence value and for discovering existing sequences.

When using the Cayenne key caching mechanism, make sure that sequences in the database have "INCREMENT BY" greater or equal to the generator "pkCacheSize" property value. If this is not the case, you will need to adjust the PkGenerator value accordingly. For example when a sequence is incremented by 1 each time, use the following code: 

dataNode.getPkGenerator().setPkCacheSize(1);
Since:
5.0

  • Constructor Details

    • SequencePkGenerator

      protected SequencePkGenerator(JdbcAdapter adapter)

  • Method Details

    • createAutoPk

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

    • createAutoPkStatements

      public List<String> createAutoPkStatements(List<DbEntity> dbEntities)
      Creates a list of CREATE SEQUENCE statements for the list of DbEntities.
      Specified by:
      createAutoPkStatements in interface PkGenerator
      Overrides:
      createAutoPkStatements in class JdbcPkGenerator

    • dropAutoPk

      public void dropAutoPk(DataNode node, List<DbEntity> dbEntities)
      Drops PK sequences for all specified DbEntities.
      Specified by:
      dropAutoPk in interface PkGenerator
      Overrides:
      dropAutoPk in class JdbcPkGenerator
      Parameters:
      node - node that provides access to a DataSource.
      dbEntities - a list of entities whose primary key auto-generation support should be dropped.

    • dropAutoPkStatements

      public List<String> dropAutoPkStatements(List<DbEntity> dbEntities)
      Creates a list of DROP SEQUENCE statements for the list of DbEntities.
      Specified by:
      dropAutoPkStatements in interface PkGenerator
      Overrides:
      dropAutoPkStatements in class JdbcPkGenerator

    • createSequenceString

      protected String createSequenceString(DbEntity ent)

    • dropSequenceString

      protected String dropSequenceString(DbEntity ent)
      Returns a SQL string needed to drop any database objects associated with automatic primary key generation process for a specific DbEntity.

    • selectNextValQuery

      protected abstract String selectNextValQuery(String pkGeneratingSequenceName)
      Returns a database-specific query to fetch the next value of the named sequence.

    • selectAllSequencesQuery

      protected abstract String selectAllSequencesQuery()
      Returns a database-specific query that lists the names of all existing sequences.

    • longPkFromDatabase

      protected long longPkFromDatabase(DataNode node, DbEntity entity)
      Generates a primary key by calling the database sequence corresponding to the dbEntity.
      Overrides:
      longPkFromDatabase in class JdbcPkGenerator
      Since:
      3.0

    • pkCacheSize

      protected int pkCacheSize(DbEntity entity)

    • sequenceName

      protected String sequenceName(DbEntity entity)

    • getSequencePrefix

      protected String getSequencePrefix()

    • getExistingSequences

      protected List<String> getExistingSequences(DataNode node)
      Fetches a list of existing sequences that might match Cayenne generated ones.