Sun GlassFish Enterprise Server 2.1 Developer's Guide

CMP Restrictions and Optimizations

This section discusses restrictions and performance optimizations that pertain to using CMP.

Disabling ORDER BY Validation

EJB QL as defined in the EJB 2.1 Specification defines certain restrictions for the SELECT clause of an ORDER BY query (see section 11.2.8 ORDER BY Clause). This ensures that a query does not order by a field that is not returned by the query. By default, the EJB QL compiler checks the above restriction and throws an exception if the query does not conform.

However, some databases support SQL statements with an ORDER BY column that is not included in the SELECT clause. To disable the validation of the ORDER BY clause against the SELECT clause, set the DISABLE_ORDERBY_VALIDATION JVM option as follows:

asadmin create-jvm-options --user adminuser

The DISABLE_ORDERBY_VALIDATION option is set to false by default. Setting it to true results in a non-portable module or application.

Setting the Heap Size on DB2

On DB2, the database configuration parameter APPLHEAPSZ determines the heap size. If you are using the Sun GlassFish or DataDirect database driver, set this parameter to at least 2048 for CMP. For more information, see

Eager Loading of Field State

By default, the EJB container loads the state for all persistent fields (excluding relationship, BLOB, and CLOB fields) before invoking the ejbLoad method of the abstract bean. This approach might not be optimal for entity objects with large state if most business methods require access to only parts of the state.

Use the fetched-with element in sun-cmp-mappings.xml for fields that are used infrequently. See fetched-with in Sun GlassFish Enterprise Server 2.1 Application Deployment Guide.

Restrictions on Remote Interfaces

The following restrictions apply to the remote interface of an EJB 2.1 bean that uses CMP:

Dependent value classes can be exposed in the remote interface or remote home interface, and can be included in the client EJB JAR file.

PostgreSQL Case Insensitivity

Case-sensitive behavior cannot be achieved for PostgresSQL databases. PostgreSQL databases internally convert all names to lower case, which makes the following workarounds necessary:

No Support for lock-when-loaded on Sybase

For EJB 2.1 beans, the lock-when-loaded consistency level is implemented by placing update locks on the data corresponding to a bean when the data is loaded from the database. There is no suitable mechanism available on Sybase databases to implement this feature. Therefore, the lock-when-loaded consistency level is not supported on Sybase databases. See consistency in Sun GlassFish Enterprise Server 2.1 Application Deployment Guide.

Sybase Finder Limitation

If a finder method with an input greater than 255 characters is executed and the primary key column is mapped to a VARCHAR column, Sybase attempts to convert type VARCHAR to type TEXT and generates the following error:

com.sybase.jdbc2.jdbc.SybSQLException: Implicit conversion from datatype 
'TEXT' to 'VARCHAR' is not allowed.  Use the CONVERT function to run this 

To avoid this error, make sure the finder method input is less than 255 characters.

Date and Time Fields

If a field type is a Java date or time type (java.util.Date, java.sql.Date, java.sql.Time, java.sql.Timestamp), make sure that the field value exactly matches the value in the database.

For example, the following code uses a java.sql.Date type as a primary key field:

java.sql.Date myDate = new java.sql.Date(System.currentTimeMillis())
BeanA.create(myDate, ...);

For some databases, this code results in only the year, month, and date portion of the field value being stored in the database. Later if the client tries to find this bean by primary key as follows, the bean is not found in the database because the value does not match the one that is stored in the database.

myBean = BeanA.findByPrimaryKey(myDate);

Similar problems can happen if the database truncates the timestamp value while storing it, or if a custom query has a date or time value comparison in its WHERE clause.

For automatic mapping to an Oracle database, fields of type java.util.Date, java.sql.Date, and java.sql.Time are mapped to Oracle’s DATE data type. Fields of type java.sql.Timestamp are mapped to Oracle’s TIMESTAMP(9) data type.


For version consistency triggers on MSSQL, the property RECURSIVE_TRIGGERS must be set to false, which is the default. If set to true, triggers throw a java.sql.SQLException.

Set this property as follows:

EXEC sp_dboption 'database-name', 'recursive triggers', 'FALSE'

You can test this property as follows:

SELECT DATABASEPROPERTYEX('database-name', 'IsRecursiveTriggersEnabled')

MySQL Database Restrictions

The following restrictions apply when you use a MySQL database with the Enterprise Server for persistence.