About lock

forum_thread

Some technical questions

Hi, ObjectDB looks interesting. Have two technical questions... (1) what locking model does ObjectDB use? I.e. 2PL or MVCC? Do writers block readers? Do readers block writers? (2) what's the recommended usage for SAAS? One ObjectDB database per customer, or one ObjectDB database for all? Thank you, Andrej #1 2011-09-19 19:15 Hi, ObjectDB looks interesting. Have two technical questions... (1) what locking model does Objec ...

 
forum_thread

Attempt to open a non existing file '/tmp/objectdb_xxxx/SortQueryItr_6.mrg'

Hi, I came across an error - but i have not been able to create a simple reproducible case - the error does not happen often and does not happen always -  Let me explain: 1/ I run 5 java applications at the same time on one machine - each application is using an ODB file (each one is using a different one). Basically each application does a sorted query ( qqq = em.createQuery("SELECT bk FROM OBN bk ORDER BY bk.time ASC", OBN); ) 2/ after a little while - some of the applications throws this error message: ... of each temporary directory. In that directory a lock file, lock.lck , is created and hold for the life of the process (or class loader). ...

 
api-jpa

PessimisticLockScope.EXTENDED

In addition to the behavior for PessimisticLockScope.NORMAL, element collections and relationships owned by the entity that are contained in join tables will be locked if the javax.persistence.lock.scope property is specified with a value of PessimisticLockScope.EXTENDED.(Enum Constant of javax.persistence.PessimisticLockScope)

 
manual

JPA Named Queries

Explains how to define and how to run JPA named queries.... annotation element (Optional) The lock mode type to use in query execution. See JavaDoc Reference Page... ... setLockMode(lockMode) Query's method Set the lock mode type to be used for the query execution. See JavaDoc Reference ...

 
forum_thread

How to do multithreading with embedded ObjectDB

Hi, I've tried to implement a counter with ObjectDB, but the following code doesn't work as expected: ... than concurrently: synchronized ( lock ) { em. createQuery ( "UPDATE Point ... ( ) ; } Your lock object must be one object that is shared by all the threads. 2. ...

 
manual

[ODB1] Chapter 6 - Persistent Objects

Shows how to store, retrieve, update and delete database objects. ... in section 5.3 , ObjectDB manages an automatic lock mechanism in order to prevent two or more different PersistenceManager ... When a JDOHelper.isDirty(obj) is true a WRITE lock is used and when it is false a READ lock is used. When the state of ...

 
api-jdo

javax.jdo.Transaction

The JDO Transaction interface provides for initiation and completion of transactions under user control.(Interface of JDO)

 
forum_thread

Setting temp directory location in ObjectDB

HI, I am using ObjectDB and would to change the temp directory location wihtout using objectDB.conf file. I am using JDO and setting the persistenceManager as follow properties.setProperty("javax.jdo.PersistenceManagerFactoryClass","com.objectdb.jdo.PMF"); properties.setProperty("javax.jdo.option.ConnectionURL", fileName.odb); pmf = JDOHelper.getPersistenceManagerFactory(properties), JDOHelper.class.getClassLoader()); #1 2011-08-02 15:49 HI, I am using ObjectDB and would to change the temp directory location wihtout using objectDB.conf fil ...

 
forum_thread

Transaction isolation support?

I am looking at using ObjectDB for our new project, and its looking good so far. But I have been unable to find any documentation about how transaction isolation is handled. For example: What happens If I am reading data in transaction A, and then transaction B commits while A is reading. (Especially if using LAZY fetch sub object). Do I always just get the list of objects as it looks when the fetch start? Martin   #1 2013-04-14 13:16 I am looking at using ObjectDB for our new project, and its looking good so far. But I have been unable to find a ...

 
forum_thread

Failed to commit transaction: Attempt to commit a rollback only transaction

Anyone know what this means?? Suddenly cropped up.   Failed to commit transaction: Attempt to commit a rollback only transaction (error 613) at com.objectdb.jpa.EMImpl.commit(EMImpl.java:271) at javax.jdo.Transaction$commit.call(Unknown Source) #1 2011-05-24 22:22 Anyone know what this means?? Suddenly cropped up. Failed to commit transaction: Attempt to commit ...