About @Version

forum_thread

Extra uninitialised entities spawned on merge()

In the following, Element is a base entity class, with a bi-directional @ManyToOne-@OneToMany relationship Element owner - List<Element> ownedElements, and Example is a subclass entity with a relationship @OneToOne Element child. #1 2012-06-05 03:25 In the following, Element is a base entity class, with a bi-directional @ManyToOne-@OneToMany relationship Elem ...

 
forum_thread

Type xxx is not found (error 301)

The error: Type User is not found (error 301) occurs when I query the db for a type before any instances of that type have been persisted, e.g.: return em.createQuery ("SELECT a FROM User a").getResultList (); What I was expecting was an empty list, not an error. Is there some enhancement that should be done beforehand?   #1 2010-11-11 09:24 The error: Type User is not found (error 301) occurs when I query the db for a type before any in ...

 
forum_thread

remove() and persist() in same transaction => Attempt to reuse an existing primary key value

Hello Support, in our configuration (FlushModeType.AUTO) is the execution of  em.find(Entity.class, <id>) much faster than an equivalent query. To optimize the Performance we define a special Entity (A) with additional data that use an existing ID of another Entity (B) from another class (another table). On this point we get no conflicts. If we remove additional data for Entity (B) and then the special Entity (A) is empty, we remove the special Entity (A). #1 2017-02-22 06:53 Hello Support, in our configuration (FlushModeType.AUTO) is the execution of  em.find(Entity.class, ...

 
manual

Query Parameters in JPA

Explains how to use parameters (named parameters and ordinal parameters) in JPA queries. Query parameters enable the definition of reusable queries. Such queries can be executed with different parameter values to retrieve different results. Running the same query multiple times with different parameter values (arguments) is more efficie ...

 
forum_thread

Check for index existence ?

Hello, Is there a simple way to check if indexes specified in entities are well taken into account by ObjectDb ? Regards, Xirt #1 2016-08-06 16:09 Hello, Is there a simple way to check if indexes specified in entities are well taken into account by Obj ...

 
forum_thread

Changes in detach behaviour?

Hello! Today i upgraded to 2.3.5_04. My program stopped working. After some debugging i found out that all fields of retrieved objects are on their default value till i first call a getter or detach them explicitly. Up to 2.3.4 they where initialized immediately. The problem in my case is that i have a Spring DAO. It does the following: I call for example getUserByName("blub). #1 2011-12-28 10:31 Hello! Today i upgraded to 2.3.5_04. My program stopped working. After some debugging i found out that al ...

 
manual

Index Definition

Describes how to define indexes in JPA entity classes and explains how indexes are used in JPQL queries. Querying without indexes requires iteration over entity objects in the database one by one. This may take a significant amount of time if many entity objects have to be examined. Using proper indexes the iteration can be avoided and complex queries ov ...

 
manual

Logical Operators in JPQL and Criteria API

Explains how to use AND, OR and NOT in JPQL queries. Logical operators in JPQL and in JPA criteria queries enable composition of complex JPQL boolean expressions out of simple JPQL boolean expressions. This page covers the following topics: Logical Operators ...

 
forum_thread

Using Enum type in NamedQuery: Field is not found in type

I'm trying to switch an application that worked fine in Hibernate to ObjectDB and am having issues with queries that reference enum types. On my entity object is a static enum public static enum Type {     A,B,C } that is stored in an @Enumerated member variable private Type type; @Enumerated public Type getType() {     return type; } I then try to query this field in the following JPA Named Query #1 2013-01-17 22:17 I'm trying to switch an application that worked fine in Hibernate to ObjectDB and am having issues with queri ...

 
forum_thread

Eager Fetch is not stable for collection or map types?

Hi, thanks very much for your helpful software. The problem is the storage of collection or map types is not stable, we lost them sometimes after JVM restarted. Eager fetch is properly set.And we still found that the storage is stable when we not use generic, such as "private List users = new ArrayList();" instead of "private List<User> users = new ArrayList<User>();".   The code about entity and fetch is: #1 2011-11-22 12:19 Hi, thanks very much for your helpful software. The problem is the storage of collection or map types is not ...