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the map key for associations of type java.util.Map when the map key is itself the primary key or a persistent field or property of the entity that is the value of the map. If a persistent field or property other than the primary key is used as a map key then it is expected to have a uniqueness constraint

SELECT clause (JPQL / Criteria API)

clause. Collection and map fields cannot be included in the results directly, but their content

Index Definition

; : } Indexes in Queries ObjectDB manages a BTree for every index. A BTree is an ordered map data

What are the main benefits of using ObjectDB?

the execution time of object oriented applications significantly. For instance, collection and map

Can I use ObjectDB to access a relational database?

To access relational databases using the Java Persistence API (JPA) you will need an Object Relational Mapping (ORM) tool, such as Hibernate, TopLink, EclipseLink, Open JPA or DataNucleus. The DataNucleus ORM implementation supports also the Java Data Objects (JDO) API. ObjectDB is a full featured

Deleting JPA Entity Objects

objects. Orphan removal can also be set for collection and map fields. For example: @Entity class

Entity Management Settings

class, which is not an entity class, mapped super class or embeddable class). The <cascade-persist

JPA Annotations for Classes

JPA defines three types of persistable classes which are set by the following annotations: Chapter 2 of the ObjectDB manual explains these annotations in detail. Entity and mapped super classes can be further configured by annotations that specify cache preferences and lifecycle event listener


variableDeclaration, String candidateCollectionExpression, Map parameters) Add a subquery to this query. Add a subquery to this query. The Map version of the method treats the key of each map entry as ... for either the parameter or the value of the String[], or for any map key or value, that expression is ignored


getMapping() Get the Mapping setting for this factory. Get the Mapping setting for this factory. This is used to find the object-datastore mapping file(s). Returns: the Mapping setting. Since: JDO 1.0 ... setMapping(String mapping) Set the Mapping setting for this factory. Set the Mapping setting

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

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