Fast Object Database for Java - with JPA/JDO support

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Method javax.persistence.criteria.CriteriaBuilder Expression> keys( M map ) Create an expression that returns the keys of a map. Parameters: map - map Returns: set expression Since: JPA 2.0


Annotation Element javax.jdo.annotations.Key String unique Whether the element column(s) contents should be considered unique Returns: whether the element column(s) contents should be considered unique Default value: "" Since: JDO 2.1


Annotation Element javax.jdo.annotations.Key String indexed Whether the value column(s) should be indexed. Returns: whether the value column(s) should be indexed. Default value: "" Since: JDO 2.1


Annotation Element javax.jdo.annotations.Key String index The name of the index to generate. Returns: the name of the index Default value: "" Since: JDO 2.1


Annotation Element javax.jdo.annotations.Key Extension[] extensions Vendor extensions. Returns: the vendor extensions Default value: {} Since: JDO 2.1


(Class entityClass, Object primaryKey) Find by primary key. Find by primary key. Search for an entity of the specified class and primary key. If the entity instance is contained in the persistence context, it is returned from there. Parameters: entityClass - entity class primaryKey - primary key

JPA Annotations for Value Generation

Automatically generated values are mainly useful for primary key fields, but are supported by ObjectDB also for regular (non primary key) persistent fields. At the field level, the @GeneratedValue with an optional GenerationType strategy is specified: The @GeneratedValue annotation

ORDER BY clause (JPQL / Criteria API)

. The following query returns Country objects ordered by currency as the primary sort key and by name as the secondary sort key: SELECT c.currency, FROM Country c ORDER BY c.currency, ... this case, the first expression is the primary order expression. Any additional order expression

JPA Annotations for Classes

are useful in representing composite primary keys as explained in the Primary Key section of the ObjectDB manual.


get methods) Specifies a primary key column that is used as a foreign key to join to another table ... to a primary table; and it may be used in a OneToOne mapping in which the primary key ... to have the same names as the primary key columns of the primary table of the superclass. Example

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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