Class EmpressDictionary

java.lang.Object
org.apache.openjpa.jdbc.sql.DBDictionary
org.apache.openjpa.jdbc.sql.EmpressDictionary
All Implemented Interfaces:
JoinSyntaxes, Configurable, IdentifierConfiguration, ConnectionDecorator, LoggingConnectionDecorator.SQLWarningHandler

public class EmpressDictionary extends DBDictionary
Dictionary for Empress using ODBC server combined with their type 2 driver. This dictionary may issues with other driver/topology configurations. Empress does not allow multiple connections to read rows read in a transaction, effectively forcing pessimistic transactions regardless of the Optimistic setting. To allow users to use optimistic transactions in a multi-connection evironment, you must set the AllowConcurrentRead setting to true in addition to standard options. Empress has the following additional limitations:
  • Foreign keys are quite limited in Empress and it is recommended that these be created by hand.
  • Batching can be unreliable. Using BatchLimit=0 is strongly recommended.
  • Using AllowConcurrentRead should be accompanied by SimulateLocking=true
  • Connections should be rolled back on return to ensure locks are released (see OpenJPA default DataSource documentation.
  • Certain outer joins requiring parameters in a subselect is not supported by Empress and may under certain configurations cause size () calls on query results and LRS fields to throw an exception.
  • Certain aggregate functions are not supported.
  • Field Details

    • allowConcurrentRead

      public boolean allowConcurrentRead
      This setting inserts "BYPASS" after every "SELECT". This allows for multiple transactional reads of the same row from different connections at the expense of loss of pessimistic locking. Defaults to false.
  • Constructor Details

    • EmpressDictionary

      public EmpressDictionary()
  • Method Details