EclipseLink/Examples/JPA/Migration/OpenJPA/QueryHints

Migrating OpenJPA to EclipseLink JPA: Query Hints

NOTE: Under Construction

Within a JPA application there is support for specifying query hints which define provider specific behaviour. These hints can be specified in annotations, within the ORM XML files, or within application code. The query hint names are strings and therefore do not typically force compile time dependencies on a particular provider but the values for these hints may introduce dependencies. The following sections outline OpenJPA query hints and their corresponding EclipseLink JPA features. If any query hint related migration information is missing or incomplete please log a documentation enhancement request referencing this page and provide details of your migration challenge.

Note: This migration information is based on the OpenJPA 1.2.1 documentation.

OpenJPA Hint	Description	EclipseLink JPA Equivalent Functionality
openjpa.hint.OracleSelectHint	Specifies an Oracle specific query hint to be generated	eclipselink.sql.hint
openjpa.FetchPlan.ReadLockMode	Values= READ or WRITE	JPA 2.0's Query.setLokMode(LockModeType)
openjpa.hint.OptimizeResultCount	Integer value greater than zero	QueryHints.JDBC_FETCH_SIZE
openjpa.FetchPlan.Isolation
openjpa.FetchPlan.MaxFetchDepth		FetchGroup depth specified by attributes in EclipseLink and not by numeric depth
openjpa.FetchPlan.FetchBatchSize		Query.setMaxResults QueryHints.JDBC_MAX_ROWS
openjpa.FetchPlan.LockTimeOut	Number of ms to wait to acquire a lock (-1 means no limit)	QueryHints.PESSIMISTIC_LOCK_TIMEOUT
openjpa.FetchPlan.EagerFetchMode		FetchGroup loading is done based on attributes specified or in the case of the default FetchGroup the lazy configuration of the mappings.
openjpa.FetchPlan.SubclassFetchMode	Determines how to eager-fetch subclass data	FetchGroup attributes can be for any mapped attribute in the target entity or its mapped parent classes.