CREATE TABLE job (
id      INT PRIMARY KEY AUTO_INCREMENT,
owner   VARCHAR(50),
status  VARCHAR(10) );

START TRANSACTION;
INSERT INTO job (owner, status)
SELECT 'fred', 'init' FROM DUAL
WHERE NOT EXISTS
(   SELECT 1 FROM job
    WHERE owner = 'fred' AND status IN ('init', 'running')
);
COMMIT;

@Lock(LockModeType.READ)
long countByOwnerAndSeatIdAndStatusIn(String owner, List<String> status);

@Transactional
public Job createJob(Job job) {
    if (jobRepository.countByOwnerAndStatusIn(job.getOwner(), Job.PROGRESS_STATUS) == 0) {
        // Sleeps just to ensure conflicts
        Thread.sleep(1000);
        Job newJob = jobRepository.save(job);
        Thread.sleep(1000);
        return newJob
    }
    else {
        return null;
    }
}