Enabled JDBC batch processing hides SQL exception

Steps to reproduce:

1. Setup Camunda DB schema based on 7.12 on Postgresql
2. Break the DB schema, for example, by deleting the column ACT_RU_JOB#REPEAT_OFFSET_
3. Start Camunda (with jdbcBatchProcessing = true)
4. Deploy a BPMN process containing a timer event
5. Start a process instance

Expected behavior:

• The engine fails to insert the timer because of the missing column REPEAT_OFFSET_
• The respective exception message contains the database exception pointing out that the column REPEAT_OFFSET_ is not present, e.g.,

  ENGINE-03004 Exception while executing Database Operation 'INSERT TimerEntity[ca202cdf-7a75-11ea-86ee-0242ac12000a]' with message '
  ### Error updating database.  Cause: org.postgresql.util.PSQLException: ERROR: column "repeat_offset_" of relation "act_ru_job" does not exist
    Position: 397
  ### The error may involve org.camunda.bpm.engine.impl.persistence.entity.JobEntity.insertTimer-Inline
  ### The error occurred while setting parameters
  ### SQL: insert into ACT_RU_JOB (             ID_,             TYPE_,             LOCK_OWNER_,             LOCK_EXP_TIME_,             EXCLUSIVE_,             EXECUTION_ID_,             PROCESS_INSTANCE_ID_,             PROCESS_DEF_ID_,             PROCESS_DEF_KEY_,             RETRIES_,             EXCEPTION_STACK_ID_,             EXCEPTION_MSG_,             DUEDATE_,             REPEAT_,             REPEAT_OFFSET_,             HANDLER_TYPE_,             HANDLER_CFG_,             DEPLOYMENT_ID_,             SUSPENSION_STATE_,             JOB_DEF_ID_,             PRIORITY_,             SEQUENCE_COUNTER_,             TENANT_ID_,             CREATE_TIME_,             REV_           )     values (?,             'timer',             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             1     )
  ### Cause: org.postgresql.util.PSQLException: ERROR: column "repeat_offset_" of relation "act_ru_job" does not exist
  ...
  

Observed behavior:

• The engine fails to insert the timer because of the missing column REPEAT_OFFSET_
• But the exception message does not provide any information on while the insert failed, e.g.,

  ENGINE-03004 Exception while executing Database Operation 'INSERT TimerEntity[fd286b14-73e9-11ea-b3fd-0242ac12000b]' with message '
  ### Error flushing statements.  Cause: org.apache.ibatis.executor.BatchExecutorException: org.camunda.bpm.engine.impl.persistence.entity.JobEntity.insertTimer (batch index #3) failed. 2 prior sub executor(s) completed successfully, but will be rolled back. Cause: java.sql.BatchUpdateException: Batch entry 0 insert into ACT_RU_JOB (
              ID_,
              TYPE_,
              LOCK_OWNER_,
              LOCK_EXP_TIME_,
              EXCLUSIVE_,
              EXECUTION_ID_,
              PROCESS_INSTANCE_ID_,
              PROCESS_DEF_ID_,
              PROCESS_DEF_KEY_,
              RETRIES_,
              EXCEPTION_STACK_ID_,
              EXCEPTION_MSG_,
              DUEDATE_,
              REPEAT_,
              REPEAT_OFFSET_,
              HANDLER_TYPE_,
              HANDLER_CFG_,
              DEPLOYMENT_ID_,
              SUSPENSION_STATE_,
              JOB_DEF_ID_,
              PRIORITY_,
              SEQUENCE_COUNTER_,
              TENANT_ID_,
              CREATE_TIME_,
              REV_
            )
      values ('fd286b14-73e9-11ea-b3fd-0242ac12000b',
              'timer',
              NULL,
              NULL,
              '1',
              'fd25d302-73e9-11ea-b3fd-0242ac12000b',
              'b916e17d-73e9-11ea-b3fd-0242ac12000b',
              'process:1:90ea74f7-73e9-11ea-b3fd-0242ac12000b',
              'process',
              3,
              NULL,
              NULL,
              '2020-04-01 07:25:45.008000 +00:00',
              NULL,
              0,
              'timer-intermediate-transition',
              'foo',
              '90e1c264-73e9-11ea-b3fd-0242ac12000b',
              1,
              '90ea9c08-73e9-11ea-b3fd-0242ac12000b',
              0,
              1,
              NULL,
              '2020-04-01 07:25:40.008000 +00:00',
              1
      ) was aborted.  Call getNextException to see the cause. Flush summary: 
   [
  ...
  ]
  at org.camunda.bpm.engine.impl.db.EnginePersistenceLogger.flushDbOperationException(EnginePersistenceLogger.java:131)
  at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flushDbOperations(DbEntityManager.java:355)
  at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flushDbOperationManager(DbEntityManager.java:322)
  at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flush(DbEntityManager.java:294)
  at org.camunda.bpm.engine.impl.interceptor.CommandContext.flushSessions(CommandContext.java:263)
  at org.camunda.bpm.engine.impl.interceptor.CommandContext.close(CommandContext.java:186)
  ...
  

Hint:

• To get the actual exception, the user has to disable JDBC batch processing in the process engine configuration.
• For example, the difference between 7.11.0 and 7.12.0 is:
  • 7.11.0: The method #flushDbOperationsException() is called which went over #getNextException() to collect all exceptions, see https://github.com/camunda/camunda-bpm-platform/blob/7.11.0/engine/src/main/java/org/camunda/bpm/engine/impl/db/entitymanager/DbEntityManager.java#L362
  • 7.12.0: The method #flushDbOperationException() is called which gets only the exception which will be used to get the exception message but it does not "resolve" the next exceptions by calling #getNextException().
• With the 7.10.0 and 7.11.0 the engine logged, for example, DB2 SQL exceptions like this:

  ENGINE-03083 Exception while executing Batch Database Operations with message '
  ### Error flushing statements. Cause: org.apache.ibatis.executor.BatchExecutorException: org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.deleteExecution (batch index #8) failed. 7 prior sub executor(s) completed successfully, but will be rolled back. Cause: com.ibm.db2.jcc.am.BatchUpdateException: [jcc][t4][102][10040][4.19.26] Batch failure. The batch was submitted, but at least one exception occurred on an individual member of the batch.
  Use getNextException() to retrieve the exceptions for specific batched elements. ERRORCODE=-4229, SQLSTATE=null
  ### Cause: org.apache.ibatis.executor.BatchExecutorException: org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.deleteExecution (batch index #8) failed. 7 prior sub executor(s) completed successfully, but will be rolled back. Cause: com.ibm.db2.jcc.am.BatchUpdateException: [jcc][t4][102][10040][4.19.26] Batch failure. The batch was submitted, but at least one exception occurred on an individual member of the batch.
  Use getNextException() to retrieve the exceptions for specific batched elements. ERRORCODE=-4229, SQLSTATE=null
  com.ibm.db2.jcc.am.BatchUpdateException: [jcc][t4][102][10040][4.19.26] Batch failure. The batch was submitted, but at least one exception occurred on an individual member of the batch.
  Use getNextException() to retrieve the exceptions for specific batched elements. ERRORCODE=-4229, SQLSTATE=null
  com.ibm.db2.jcc.am.SqlIntegrityConstraintViolationException: Error for batch element #1: DB2 SQL Error: SQLCODE=-532, SQLSTATE=23504, SQLERRMC=CAMUNDA.ACT_RU_VARIABLE.ACT_FK_VAR_EXE, DRIVER=4.19.26
  com.ibm.db2.jcc.am.SqlIntegrityConstraintViolationException: Error for batch element #2: DB2 SQL Error: SQLCODE=-532, SQLSTATE=23504, SQLERRMC=CAMUNDA.ACT_RU_EXECUTION.ACT_FK_EXE_SUPER, DRIVER=4.19.26
  '. Flush summary:
   [
  ...
  ]
   at org.camunda.bpm.engine.impl.db.EnginePersistenceLogger.flushDbOperationsException(EnginePersistenceLogger.java:692)
   at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flushDbOperations(DbEntityManager.java:361)
   at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flushDbOperationManager(DbEntityManager.java:324)
   at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.flush(DbEntityManager.java:296)
  ...