ObjectDB Database Search

Databases are also supported by ObjectDB. The combination of Object Database features ... . Up to 9,223,372,036,854,775,808 entity objects per database file. Unlimited database connections ... database files (the ObjectDB Doctor ). Standard Persistence APIs ObjectDB is the only Object -Oriented

solution. Using a relational database management system (RDBMS) to store and retrieve Java objects requires slow conversions between graphs of Java objects and flat database table rows. Object Relational ... with a database . ObjectDB is an extremely easy to use pure Java Object Database , which supports JPA

. However, you should consider the following points when doing your own objective comparison of object databases : ObjectDB is unique in supporting the standard APIs. It is the only object database with built in ... of the Java Data Objects (JDO) API than competing object databases . By using a standard API such as JPA

The Java Persistence API (JPA) provides various ways to retrieve objects from the database ... of the database . The persistence context serves as a cache of retrieved entity objects . If a requested ... with data that is retrieved from the database (or from the L2 cache - if enabled). The new entity object

of a single field in a single database object . This type of viewer is useful for viewing data ... object models, is preferred. A Tree window displays objects as a tree. Every database object ... windows provide easier navigation. Because every reference between two database objects is represented by

), which can represent physical objects in the database . Managing an ObjectDB Object Database using JPA ... database objects . Entity Object Life Cycle The life cycle of entity objects consists of four states ... the database . An entity object becomes Managed when it is persisted to the database

New entity objects can be stored in the database either explicitly by invoking the persist method ... its state to Managed. The new entity object is stored in the database when the transaction ... class. Only instances of entity classes can be stored in the database independently. Objects

Detached entity objects are objects in a special state in which they are not managed by any EntityManager but still represent objects in the database . Compared to managed entity objects , detached ... the database unless modified detached objects are merged back into an EntityManager to become managed

Existing entity objects can be deleted from the database either explicitly by invoking the remove ... an object from the database it has to first be retrieved (no matter which way) and then in an active ... object is physically deleted from the database when the transaction is committed. Embedded objects

Modifying existing entity objects that are stored in the database is based on transparent ... Once an entity object is retrieved from the database (no matter which way) it can simply be modified in memory ... (); The entity object is physically updated in the database when the transaction is committed

The configuration element specifies back end ( database engine) settings that are relevant ... :    The element The element specifies the database file and page size settings: The initial attribute specifies the initial size of every new database file. The resize attribute specifies

In JPA a database connection is represented by the EntityManager interface. Therefore, in order to manipulate an ObjectDB database we need an EntityManager instance. Operations that modify database ... of EntityManagerFactory that represents the relevant database and then we can use that factory instance

entity class. This is done automatically in memory each time the entity object is loaded. The database object is only updated to the new schema when that entity object is stored to the database ... of an entity class are detected by ObjectDB. New entity objects have to be stored in the new class

Given an EntityManager , em , that represents a JPA connection to the object database , we can use it to store, retrieve, update and delete database objects . Storing New Entity Objects The following code fragment stores 1,000 Point   objects in the database : em. getTransaction (). begin

To access relational databases using the Java Persistence API (JPA) you will need an Object ... . The DataNucleus ORM implementation supports also the Java Data Objects (JDO) API. ObjectDB is a full featured standalone Object Database Management System (ODBMS) and not an ORM tool, so it is not intended and cannot be used to access other database management systems.

As noted above, using ObjectDB instead of a relational database and ORM combination  ... of a relational database is mandatory (e.g. as a result of a customer request or when a new application is developed for an existing old relational database ). By using the Java Persistence API (JPA

, but they are easier to use in object oriented languages such as Java. In addition, unlike most other NoSQL databases ... ObjectDB is a unique NoSQL database . It doesn't have the known disadvantages and limitations ... ). Therefore, ObjectDB can be used in applications that cannot use conventional non ACID NoSQL databases because of a requirement for a very high level of consistency.

A connection to a database is represented by an EntityManager instance, which also provides functionality for performing operations on a database . Many applications require multiple database ... database connection, using a separate EntityManager instance, for every HTTP request. The main role

, the same database is managed on multiple machines (nodes), possibly in different geographic locations ... master-slave replication, the master node manages the main (master) database , which supports Read / Write operations. The other (slave) nodes in the cluster manage identical copies of the same database

database file Checks a given ObjectDB database file, verifies that it is healthy and valid ... of a corrupted ObjectDB database file Repairs a corrupted ObjectDB database file by creating a new fresh database file and then copying all the recoverable data in the corrupted database file

can apply recorded database operations on a matching database backup (if available). This ability is useful for two different purposes: It enables recovery from a database failure by replaying ... & Recording Files When recording is enabled , ObjectDB maintains for every database file a recording

ObjectDB Server is a tool that manages ObjectDB databases in a separate dedicated process, making these databases accessible to client applications in other processes including ones on other remote ... are: The ability to access and use databases from different processes simultaneously. The ability to access

All about ObjectDB Database in Java/JPA database - explanations, examples, references, links and related information.

Describes the ObjectDB object database tools - the Explorer, the Server, the Enhancer, the Doctor and the Replayer.

Every entity object that is stored in the database has a primary key. Once assigned, the primary key cannot be modified. It represents the entity object as long as it exists in the database . As an object database , ObjectDB supports implicit object IDs, so an explicitly defined primary key is not

in ObjectDB (and in JPA) is always at the database object level, i.e. each database object is locked separately. Optimistic locking is applied on transaction commit. Any database object ... is being performed on an old version of a database object , for which another update has already been committed

are query identification variables that iterate over all the database objects of a specific entity ... over all the Country objects in the database : SELECT c FROM Country AS c The AS keyword is optional ... is required when using multiple range variables. Iteration over about 1,000,000 database objects

for managed entity objects , including transparent navigation to other database objects , transparent update ... The ability to retrieve managed entity objects is a major advantage of JPQL. For example, the following query returns Country objects that become managed by the EntityManager em : TypedQuery query

the @Transient annotation). Storing an entity object in the database does not store methods or code ... for every entity object . The initial version of a new entity object (when stored in the database ... that do not participate in persistence and their values are never stored in the database (similar

As explained in chapter 2 , entity objects can be deleted from the database by ... the database , but when executed, delete specified entity objects from the database . Removing entity objects from the database using a DELETE query may be slightly more efficient than retrieving entity objects

To be able to store Point objects in the database using JPA we need to define an entity class ... that is marked (annotated) as having the ability to represent objects in the database . Conceptually ... class, and accordingly, provides the ability to store Point objects in the database and retrieve

, which is a Long object reflecting the number of Country objects in the database : TypedQuery query = em ... . In other cases our expectation for a single object result might fail, depending on the database ... . If the database contains multiple Country objects with the name 'Canada' (e.g. due to a bug

. If an entity object is not available also in the shared cache - it is retrieved from the database and added ... Every EntityManager owns a persistence context , which is a collection of all the entity objects ... an entity object that is already managed by the  EntityManager returns the existing instance from

, but when executed, update the content of specified entity objects in the database . Updating entity objects in the database using an UPDATE query may be slightly more efficient than retrieving entity objects ... Existing entity objects can be updated, as explained in chapter 2 , by: Retrieving

clause. When a GROUP BY clause exists in a JPQL query, database objects (or tuples of database objects ... over all the Country objects in the database . The GROUP BY clause groups these Country objects by ... properties of generated groups instead of individual objects and fields. The position of a GROUP BY

class can only be stored in the database as embedded objects , i.e. as part of a containing entity ... The term persistable types refers to data types that can be used for storing data in the database ... can be stored in the database directly. Other persistable types can be embedded in entity classes as fields

to iterate over all the Country objects in the database . For a country with no capital city, such as ... returns the number of all the entity objects in the database , excluding Country entity objects ... are assigned as arguments. Path expressions that navigate from one object to another. Instances of user

rather than just field values from database tables, as with SQL. That makes JPQL more object oriented friendly ... Query The following query retrieves all the Country objects in the database : SELECT c FROM Country ... over objects in the database . A query variable that is bound to an entity class is referred to as a range

). @PostPersist - after storing a new entity in the database (during commit or flush ). @PostLoad - after an entity has been retrieved from the database . @PreUpdate - when an entity is identified as modified by the EntityManager . @PostUpdate - after updating an entity in the database (during commit or flush

The ObjectDB Object Database ObjectDB is a powerful Object -Oriented Database Management ... Features 100% pure Java Object -Oriented Database Management System (ODBMS). No proprietary API ... , JBoss and Spring. See the  ObjectDB Object Database Features  for more details.

The Java Data Objects (JDO) is another standard for accessing persistent data in databases , using ... with both relational and object databases . JDO is supported by many object databases , including ObjectDB, and it is probably the most popular Java API for object databases today.

JPQL query that retrieves selective objects from the database . Out of the four optional clauses ... over all the Country objects in the database using the c range variable. Before passing these Country ... with millions of objects in the database there is a huge difference in query execution time if proper

in Query and TypedQuery support method chaining (by returning the query object on which they were invoked). Flush Mode (setFlushMode) Changes made to a database using an EntityManager em can be visible ... is executed, uncommitted database changes (if any) have to be flushed to the database in order

ObjectDB is an Object Oriented Database Management System (ODBMS). It provides all the standard database management services (storage and retrieval, transactions, lock management, query processing ... objects (and graphs of objects ) in an ObjectDB database directly. There's no need to define tables

: Exceptions can also be thrown on an attempt to retrieve entity objects from the database . For example ... (above) may also be thrown during retrieval, if database lock has been requested for retrieved entity objects and it cannot be granted. ... JPA exceptions are represented by a hierarchy of unchecked exceptions: java.lang. Object java.lang

(as classes and objects ). ObjectDB is the only database management system with built in support ... The Java Persistence API (JPA) is a standard API for accessing databases  from within Java applications. The main advantage of JPA over JDBC (the older Java API for interacting with databases

number generator for every database . This number generator is used to generate automatic object IDs for entity objects with no primary key fields defined (as explained in the previous section ). The same ... for every new entity object . These generated values are unique at the database level and are never recycled

Operations on the database will be performed by an instance of a Data Access Object (DAO ... - for storing a new  Guest entity object in the database . getAllGuests - for retrieving all the existing  Guest objects from the database . By using Spring components we can move some work from

Operations on the database will be performed by an instance of a Data Access Object (DAO ... - for storing a new  Guest entity object in the database . getAllGuests - for retrieving all the existing  Guest objects from the database . By using Spring components we can move some work from

databases is more important than general portability to both object and relational databases . JPA is designated to be used mainly with relational databases . ObjectDB is the only object database ... databases and it is probably the most popular Java API for object databases today.