Fast Object Database for Java - with JPA/JDO support

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JDO vendors only for instances of persistence capable classes using application-managed (primary key ... the transaction, by the application modifying one or more of the application key fields, then this method


Annotation Element javax.jdo.annotations.Element String generateForeignKey Generate or assume a foreign key constraint exists on the column or columns associated with this join. Specify "true" or "false". Returns: whether to generate or assume a primary key constraint Default value: "" Since: JDO 2.1

em.flush(); em.clear(); loosing data and not persisting managed objects

build 2.2.3_06 that should fix this bug. support Support This fix works except when the primary key ... should fix it. As a side note - ObjectDB doesn't limit the length of primary keys, but large strings as demonstrated by this test should be avoided, if possible, because a primary key whose length

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Which API should I use - JPA or JDO?

You can use ObjectDB with either the Java Persistence API (JPA) or the Java Data Objects (JDO) API. Both share similar architecture, design and abilities. When to prefer JPA JPA is more commonly used. Therefore, it might be the first choice for most new applications. You can use JPA as the primary

Should derived fields of an EmbeddedId be manually maintained by app code?

If I have an Entity which has a primary key which is derived and I am implementing it using ... this shows an Entity with an EmbeddedId where the containing Entity has a simple Primary Key, and a case which shows an Entity whose container has a Primary Key which is partly a Primary Key. 2) I


and JoinColumn annotations and constraints entailed by primary key mappings. Defaults to no additional constraints. Default value: {} Since: JPA 1.0


Annotation Element javax.persistence.TableGenerator UniqueConstraint[] uniqueConstraints (Optional) Unique constraints that are to be placed on the table. These are only used if table generation is in effect. These constraints apply in addition to primary key constraints. Defaults to no additional constraints. Default value: {} Since: JPA 1.0


is not specified, ordering by the primary key of the associated entity is assumed. Default value: "" Since: JPA 1.0


Annotation Element javax.persistence.TableGenerator String pkColumnName (Optional) Name of the primary key column in the table. Defaults to a provider-chosen name. Default value: "" Since: JPA 1.0

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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