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Online Backup

An ObjectDB database can be backed up by simply copying or archiving the database file while the database is offline (i.e. when it is not open in an ObjectDB server and not in use by any application ... ) that represents the connection (local or remote) to the database:     em.createQuery("objectdb backup

JPA Named Queries

is attached to exactly one entity class or mapped superclass - usually to the most relevant entity ... that named queries may be attached to any entity class or mapped superclass. Therefore, to be able

JPA Query Expressions (JPQL / Criteria)

] MEMBER [OF] and the [NOT] LIKE operator. Logical operators: AND, OR, NOT. In addition, JPA queries ... , isMember, isNotMember, size). Comparison expressions (equal, notEqual, gt, ge, lt, le, between, isNull, ...) Logical expressions (and, or, not, isTrue).

What are the system requirements for using ObjectDB?

ObjectDB requires Java 5 or later (Java 6 is preferred). As a pure Java application, ObjectDB should be able to run on any platform that supports the Java Standard Edition. Either the Java Development Kit (JDK) or the Java Runtime Environment (JRE) can be used. A version of ObjectDB for .NET is currently under development.

Working with JPA Entity Objects

the Configuration chapter. By default, managed entity objects that have not been modified or removed ... it and it is automatically removed from the persistence context. ObjectDB can be configured to use strong references or


the Java language. Only objects that are instances of this class (or one of its subclasses) are thrown by the Java Virtual Machine or can be thrown by the Java throw statement. Similarly, only this class or one of its subclasses can be the argument type in a catch clause. Instances of two subclasses


that will be called for every new class definition or class redefinition that gets loaded by the loader ... that will be called for every new class definition or class redefinition that gets loaded by ... any classes, resources, or open URLs. Returns ClassLoader that the provider may use to load any


whether duplicate results must be eliminated from the query result or whether they must be retained ... to the restriction(s) over the grouping items, or null if no restrictions have been specified. Return the predicate that corresponds to the restriction(s) over the grouping items, or null

Step 3: Add a Context Listener Class

a ServletContextListener to perform initialization and cleanup operations: The database will be opened (or created ... . The database will be closed when the web application stops (or when the web server shuts down), by


which to return each element of the result of invoking execute or one of its siblings. If the result is not set or set to null, the result class defaults to the candidate class of the query. If the result consists ... , String, or Object[]; or one of the java.math classes BigInteger or BigDecimal; or the java.util

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.

Need Help?

  1. Search ObjectDB website
  2. Read the FAQ
  3. Follow the Tutorials
  4. View or post in the forum
  5. Search or file an issue
  6. Contact support