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How Should I Configure objectdb.conf to Obtain 256KB Disk IO Requests and Maximize Shared PersistenceManager Entity Cache?

to give 256KB disk accesses and use PersistenceManager L1 ref=soft caching and datastore pagefile ... by a datafile access? Arbitrary data pulled from all accesses over a datastore file? Are the cache ... Does ObjectDB access the datafile in page-sized IO requests? CBE CBE Yes. support Support


Annotation Element javax.persistence.PersistenceUnit String unitName (Optional) The name of the persistence unit as defined in the persistence.xml file. If specified, the persistence unit for the entity manager factory that is accessible in JNDI must have the same name. Default value: "" Since: JPA 1.0


Annotation Element javax.persistence.PersistenceUnit String name (Optional) The name by which the entity manager factory is to be accessed in the environment referencing context; not needed when dependency injection is used. Default value: "" Since: JPA 1.0


Method javax.persistence.EntityManager Metamodel getMetamodel() Return an instance of Metamodel interface for access to the metamodel of the persistence unit. Returns: Metamodel instance Throws: IllegalStateException - if the entity manager has been closed Since: JPA 2.0


to the persistence provider runtime that data should be fetched lazily when it is first accessed

Best practise loading big data

access on a large 2 dimansional table. Internally we used a list entities which hold a list ... . We have some prominent scenarios to access these values. Creating and traversing. For the traversing we access the data block by block - in each block step by step and in each step value by value


Method javax.persistence.Query T unwrap( Class<T> cls ) Return an object of the specified type to allow access to the provider-specific API. If the provider's query implementation does not support the specified class, the PersistenceException is thrown. Parameters: cls - the class of the object


Static Field javax.jdo.spi.PersistenceCapable byte READ_WRITE_OK If jdoFlags is set to READ_WRITE_OK, then the fields in the default fetch group can be accessed for read or write without notifying the StateManager. Since: JDO 1.0


Static Field javax.jdo.spi.PersistenceCapable byte READ_OK If jdoFlags is set to READ_OK, then the fields in the default fetch group can be accessed for read without notifying the StateManager. Since: JDO 1.0


in this method. The context in which this call is made does not allow access to other persistent JDO instances. Since: JDO 2.0

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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