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Oracle® Containers for J2EE Enterprise JavaBeans Developer's Guide
10g (10.1.3.1.0)

Part Number B28221-01
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Configuring TopLink JPA Query Hints in an EJB 3.0 Query

Table 8-1 lists the TopLink EJB 3.0 JPA persistence provider query hints you can specify when you construct a JPA query, as Example 8-5 shows, or when you specify a JPA query using the @QueryHint annotation, as Example 8-6 shows. When you set a hint, you can set the value using the corresponding public static final field in the appropriate configuration class in oracle.toplink.essentials.config as follows:


Note:

To access these classes, put the appropriate OC4J persistence JAR on your classpath (see "JPA Persistence JAR Files").

Example 8-5 Specifying a TopLink JPA Query Hint

import oracle.toplink.essentials.config.HintValues;
import oracle.toplink.essentials.config.TopLinkQueryHints;

Customer customer = (Customer)entityMgr.createNamedQuery("findCustomerBySSN"). setParameter("SSN", "123-12-1234").setHint(TopLinkQueryHints.BIND_PARAMETERS, HintValues.PERSISTENCE_UNIT_DEFAULT).getSingleResult();

Example 8-6 Specifying a TopLink JPA Query Hint With @QueryHint

import oracle.toplink.essentials.config.HintValues;
import oracle.toplink.essentials.config.TopLinkQueryHints;

@Entity
@NamedQuery(
    name="findAllEmployees",
    query="SELECT * FROM EMPLOYEE WHERE MGR=1"
    hints={
        @QueryHint={name=TopLinkQueryHints.BIND_PARAMETERS, value=HintValues.PERSISTENCE_UNIT_DEFAULT}
    }
)
public class Employee implements Serializable {
    ...
}

Table 8-1 TopLink JPA Query Hints

Hint Usage Default

toplink.jdbc.bind-parameters

Control whether or not the query uses parameter binding. For more information, see "Parameterized SQL (Binding) and Prepared Statement Caching" in the Oracle TopLink Developer's Guide.

Valid values: oracle.toplink.essentials.config.HintValues

  • true: bind all parameters.

  • false: do not bind all parameters.

  • PersistenceUnitDefault: use the parameter binding setting made in your TopLink session's database login.

    For more information, see "Configuring JDBC Options" in the Oracle TopLink Developer's Guide.

Example: JPA Query API

import oracle.toplink.essentials.config.HintValues;
import oracle.toplink.essentials.config.TopLinkQueryHints;
query.setHint(TopLinkQueryHints.BIND_PARAMETERS, HintValues.TRUE);

Example: @QueryHint

import oracle.toplink.essentials.config.HintValues;
import oracle.toplink.essentials.config.TargetDatabase;
@QueryHint(name=TopLinkQueryHints.BIND_PARAMETERS, value=HintValues.PERSISTENCE_UNIT_DEFAULT);

PersistenceUnitDefault

toplink.pessimistic-lock

Control whether or not pessimistic locking is used.

Valid values: oracle.toplink.essentials.config.PessimisticLock

  • NoLock: pessimistic locking is not used.

  • Lock: TopLink issues a SELECT.... FOR UPDATE.

  • LockNoWait: TopLink issues a SELECT.... FOR UPDATE NO WAIT.

Example: JPA Query API

import oracle.toplink.essentials.config.PessimisticLock;
import oracle.toplink.essentials.config.TopLinkQueryHints;
query.setHint(TopLinkQueryHints.PESSIMISTIC_LOCK, PessimisticLock.LockNoWait);

Example: @QueryHint

import oracle.toplink.essentials.config.PessimisticLock;
import oracle.toplink.essentials.config.TopLinkQueryHints;
@QueryHint(name=TopLinkQueryHints.PESSIMISTIC_LOCK, value=PessimisticLock.LockNoWait);

NoLock

toplink.refresh

Control whether or not to update the TopLink session cache with objects that the query returns.

Valid values: oracle.toplink.essentials.config.HintValues

  • true: refresh cache.

  • false: do not refresh cache.

Example: JPA Query API

import oracle.toplink.essentials.config.HintValues;
import oracle.toplink.essentials.config.TopLinkQueryHints;
query.setHint(TopLinkQueryHints.REFRESH, HintValues.TRUE);

Example: @QueryHint

import oracle.toplink.essentials.config.HintValues;
import oracle.toplink.essentials.config.TopLinkQueryHints;
@QueryHint(name=TopLinkQueryHints.REFRESH, value=HintValues.TRUE);

false