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forum_thread

Some details about db behavior

Suppose I have two entities... A B -> A B has a ManyToOne relationship with A. When my database is empty and I persist a valid B entity (that contains actual A reference) I observe some behaviour that I'm not sure I understand. ... ManyToOne relationship with A. When my database is empty and I persist a valid B entity (that contains actual A reference) I ...

 
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?  ... ( ) ; What I was expecting was an empty list, not an error. Is there some enhancement that should be done ...

 
forum_thread

Database(*.odb) file size on disk

Hello, we have questions about the file size of ObjectDB database on disk. Can you tell us something about how the deleting of entities affects the size of *.odb files on disk? -Will the released memory always used by new entities? -Will be the database file automatically reduced?   We have created a small test, in which we create and delete entities. It looks like that the released memory are reused but the the file not resized. The database is at the end empty again, but larger than the initial size. ... but the the file not resized. The database is at the end empty again, but larger than the initial size. import java. util . ...

 
api-jpa

getEmbeddables()

Return the metamodel embeddable types.(Method of javax.persistence.metamodel.Metamodel)

 
forum_thread

ObjectDB Explorer very slow with remote con

Hi! I started to use ObjectDB Explorer to administrate a remote DB (on a server), but it seems to be very slow. The database is quite empty now, just between 5-20 records / entity, but it's still very very slow. That's the only thing that is slow on my server... How can I speed it up? ... it seems to be very slow. The database is quite empty now, just between 5-20 records / entity, but it's still very very ...

 
forum_thread

How to avoid NULL values on Embedded entities

Hi there. I'm new on this. trying to learn. I'm trying to make a value non nulleable. So, when I try to upload to the DB this field as null, it give me an error. I tried this, but it didn't work: ... code was working, the problem was that i'm savin an empty string "" (not null) edit ...

 
forum_thread

Bidirectional OneToMany is slow on updated items

Hello, I have a problem with the following situation. I insert persons with addresses. In the first run, they are all new with a new address. It runs fast. In the second run, the persons are all loaded and got a second address. This seams to be much slower. The Entities are all enhanced by the javaagent (which you can see in the contained eclipse launch configuration) Is there any way to speed it up?       ... the addressSet retrieval when the database is not empty. A simple action that can improve performance dramatically, is to ...

 
forum_thread

LEFT (OUTER) JOIN problem when mappedBy is defined

Hi all, I want to get objects with their lists, even when the lists are empty. So I've witten this query: "SELECT i FROM Invoice i LEFT OUTER JOIN i.itemList items" But this query never returns invoices without items! Only invoices with items. When I remove mappedBy from @OneToMany annotation, LEFT JOIN works correctly. Is this normal behaviour? Thank you Michael   Sample application ... to get objects with their lists, even when the lists are empty. So I've witten this query: "SELECT i FROM Invoice i LEFT ...

 
api-jpa

javax.persistence.metamodel.Metamodel

Provides access to the metamodel of persistent entities in the persistence unit.(Interface of JPA)

 
api-jpa

getDeclaredPluralAttributes()

Return all multi-valued attributes (Collection-, Set-, List-, and Map-valued attributes) declared by the managed type.(Method of javax.persistence.metamodel.ManagedType)