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JDO sequences from ORM file

>   <!-- Persistable Types with Fetch Groups -->   <class name="JdoTypes$ClassWithFetchGroup">    <fetch-group name="fg1" post-load="false">     <fetch-group name="sg1" />     <field name="p" recursion-depth="7" />    </fetch-group>   </class>   <class name="JdoTypes$ClassWithFetchGroups

Detached Entity Objects

Detached entity objects are objects in a special state in which they are not managed by any ... ). Retrieval by navigation from detached objects is not supported, so only persistent fields ... EntityManager. In addition, in JPA 2 we can detach an entity object by using the detach method: em.detach

Unexpected exception (Error 990) on find

error: [ObjectDB 2.4.7_16] Unexpected exception (Error 990) Generated by Java HotSpot(TM) 64-Bit ... -------------------------- Group #1: Page#70606 3:'Elementarprodukt:400000100317025:7:1:' 1/2 1980+609/2589 Group #2: Page#138243 3:'Elementarprodukt:400000100417179:5:1:' 1/2 1980+396/2376 Group #3: Page#165140 3

Shared (L2) Entity Cache

an entity object that is already managed by the EntityManager returns the existing instance from ... by the EntityManagerFactory and shared by all its EntityManager objects. the broader scope ... is wider, since they exist per database and are shared by all the EntityManagerFactory and EntityManager

Index Definition

Querying without indexes requires iteration over entity objects in the database one by ... A composite index is an index on more than one persistent field. It is defined by specifying multiple fields ... ; : } Notice that the paths include a collection, so multiple values will be maintained by the index

Database Connection using JPA

A connection to a database is represented by an EntityManager instance, which also provides ... . An EntityManagerFactory is constructed for a specific database, and by managing resources efficiently (e.g ... the content of a database require active transactions. Transactions are managed by an EntityTransaction

JPA Lifecycle Events

and are invoked automatically by JPA when these events occur. Internal Callback Methods Internal callback ... - when an entity is identified as modified by the EntityManager. @PostUpdate - after updating an entity in ... events by marking it with more than one annotation. By default, a callback method in a super entity


) and the active fetch groups determine the scope of fetching for the graph of instances reachable from the pc parameter. The state of fields in the affected instances is as specified by the FetchPlan. Parameters

[ODB1] Chapter 2 - A Quick Tour

by step. Both sample programs are contained in ObjectDB's samples directory. 2.1 Hello World ... ArrayList list; 18 try { 19 // Retrieve the list from the database by ... is expected to be retrieved from the database by its name "Hello World" using the getObjectById


javax.jdo.annotations Annotation FetchGroups Target: Classes Annotation for a group of fetch-group objects Since: JDO 2.1 FetchGroup[] value The Fetch Groups The Fetch Groups Returns: The Fetch Groups Since: JDO 2.1

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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