Details
Major Description
While merging object A in following relationship [ A () B (1*) C ] we get the following error. The test case is attached and I tested it with openjpa 1.0.0, 1.1.0 and 1.2.0 official releases with same error. The main problem is the error does not occur if there are just 1 or 2 C objects attached to B. If we add more C to B the probability of getting the error increases (sad but true). You can see a for loop in the test case and a constant named "MAGICAL_NUMBER". If we set the magical number to 3 or less than we don't get this error and all objects are persisted just fine. But if we increase it to 50 (to be sure) we get the error below.
There is also strange a workaround on line 63 of the test case. If we uncomment line 63 and just get the IDs of new C objects just after merge(A) but before commit () we can display proper IDs and the operation will be committed successfully. Otherwise the IDs of new C objects stay "0" (again sad but true 
. Maybe this hint can help on understanding and solving the issue.
The test case is created depending on a real life scenario. We get the same error with derby and mysql.
Here is the error after running the test case:
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 3.433 sec <<< FAILURE!
testChainEntities(org.apache.openjpa.persistence.relations.TestChainEntities) Time elapsed: 3.362 sec <<< ERROR!
<openjpa-1.1.0-r422266:659716 fatal store error> org.apache.openjpa.persistence.RollbackException: The transaction has been rolled back. See the nested exceptions for details on the errors that occurred.
at org.apache.openjpa.persistence.EntityManagerImpl.commit(EntityManagerImpl.java:523)
at org.apache.openjpa.persistence.relations.TestChainEntities.chainUpdate(TestChainEntities.java:64)
at org.apache.openjpa.persistence.relations.TestChainEntities.testChainEntities(TestChainEntities.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at org.apache.openjpa.persistence.test.PersistenceTestCase.run(PersistenceTestCase.java:122)
at junit.framework.TestSuite.runTest(TestSuite.java:208)
at junit.framework.TestSuite.run(TestSuite.java:203)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.maven.surefire.junit.JUnitTestSet.execute(JUnitTestSet.java:213)
at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.executeTestSet(AbstractDirectoryTestSuite.java:140)
at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.execute(AbstractDirectoryTestSuite.java:127)
at org.apache.maven.surefire.Surefire.run(Surefire.java:177)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:334)
at org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:980)
Caused by: <openjpa-1.1.0-r422266:659716 fatal general error> org.apache.openjpa.persistence.PersistenceException: The transaction has been rolled back. See the nested exceptions for details on the errors that occurred.
at org.apache.openjpa.kernel.BrokerImpl.newFlushException(BrokerImpl.java:2160)
at org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:2007)
at org.apache.openjpa.kernel.BrokerImpl.flushSafe(BrokerImpl.java:1905)
at org.apache.openjpa.kernel.BrokerImpl.beforeCompletion(BrokerImpl.java:1823)
at org.apache.openjpa.kernel.LocalManagedRuntime.commit(LocalManagedRuntime.java:81)
at org.apache.openjpa.kernel.BrokerImpl.commit(BrokerImpl.java:1347)
at org.apache.openjpa.kernel.DelegatingBroker.commit(DelegatingBroker.java:877)
at org.apache.openjpa.persistence.EntityManagerImpl.commit(EntityManagerImpl.java:512)
... 29 more
Caused by: <openjpa-1.1.0-r422266:659716 nonfatal general error> org.apache.openjpa.persistence.PersistenceException: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'SQL080903042502080' defined on 'CHAINENTITYC'.
FailedObject: org.apache.openjpa.persistence.relations.ChainEntityC@f6f1b6
at org.apache.openjpa.jdbc.sql.SQLExceptions.narrow(SQLExceptions.java:146)
at org.apache.openjpa.jdbc.sql.DBDictionary.newStoreException(DBDictionary.java:4150)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:102)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:72)
at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.flushAndUpdate(PreparedStatementManagerImpl.java:131)
at org.apache.openjpa.jdbc.kernel.BatchingPreparedStatementManagerImpl.flushAndUpdate(BatchingPreparedStatementManagerImpl.java:82)
at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.flushInternal(PreparedStatementManagerImpl.java:89)
at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.flush(PreparedStatementManagerImpl.java:72)
at org.apache.openjpa.jdbc.kernel.ConstraintUpdateManager.flush(ConstraintUpdateManager.java:543)
at org.apache.openjpa.jdbc.kernel.ConstraintUpdateManager.flush(ConstraintUpdateManager.java:105)
at org.apache.openjpa.jdbc.kernel.BatchingConstraintUpdateManager.flush(BatchingConstraintUpdateManager.java:56)
at org.apache.openjpa.jdbc.kernel.AbstractUpdateManager.flush(AbstractUpdateManager.java:89)
at org.apache.openjpa.jdbc.kernel.AbstractUpdateManager.flush(AbstractUpdateManager.java:72)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.flush(JDBCStoreManager.java:549)
at org.apache.openjpa.kernel.DelegatingStoreManager.flush(DelegatingStoreManager.java:130)
... 36 more
Caused by: org.apache.openjpa.lib.jdbc.ReportingSQLException: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'SQL080903042502080' defined on 'CHAINENTITYC'. {prepstmnt 18739556 INSERT INTO ChainEntityC (cId, chainEntityBId, name, optLock, CHAINENTITYB_BID) VALUES (?, ?, ?, ?, ?) [params=(long) 0, (long) 0, (String) Test_C_48, (int) 1, (long) 3651]}
[code=20000, state=23505]
at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.wrap(LoggingConnectionDecorator.java:192)
at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.access$700(LoggingConnectionDecorator.java:57)
at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator$LoggingConnection$LoggingPreparedStatement.executeUpdate(LoggingConnectionDecorator.java:866)
at org.apache.openjpa.lib.jdbc.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:269)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager$CancelPreparedStatement.executeUpdate(JDBCStoreManager.java:1398)
at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.executeUpdate(PreparedStatementManagerImpl.java:151)
at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.flushAndUpdate(PreparedStatementManagerImpl.java:120)
... 46 more
Results :
Tests in error:
testChainEntities(org.apache.openjpa.persistence.relations.TestChainEntities)
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] There are test failures.