Is it possible to change isolation level at datasource setting file in coldfusion?

wish help you to fix your issue You can set isolation level that way. Hibernate allows you to do it in a database-agnostic way, so it'll work with PostgreSQL.

will be helpful for those in need The following solution worked for me (slight modification of dimakura's answer):

acc = Account.lock.find(id)
acc.balance += 100
acc.save!

acc = Account.where(:acc_code => acc_code).first
acc.with_lock do
 acc.balance += 100
 acc.save!
end

may help you . If anyone needs the solution. The only solution I found was this:
Extend the HibernateJpaDialect class and implement the beginTransaction method to set transact isolation. It looks like this:

@Service
public class CustomHibernateJpaDialect extends HibernateJpaDialect {

    @Override
    public Object beginTransaction(final EntityManager entityManager,
            final TransactionDefinition definition) throws PersistenceException,
            SQLException, TransactionException {

        Session session = getSession(entityManager);

        if (definition.getTimeout() != TransactionDefinition.TIMEOUT_DEFAULT) {
            session.getTransaction().setTimeout(definition.getTimeout());
        }

        entityManager.getTransaction().begin();

        session.doWork(new Work() {
            public void execute(Connection connection) throws SQLException {
                DataSourceUtils.prepareConnectionForTransaction(connection, definition);
                connection.setTransactionIsolation(TransactionDefinition.ISOLATION_READ_UNCOMMITTED);
            }
        });

        return prepareTransaction(entityManager, definition.isReadOnly(), definition.getName());
    }

}

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            DataSource dataSource,
            CustomHibernateJpaDialect customHibernateJpaDialect) throws SQLException {

        LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource);

        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

        em.setJpaVendorAdapter(vendorAdapter);
        em.setJpaDialect(customHibernateJpaDialect);

        return em;
    }

wish helps you I will start by saying that I do share the belief that it's rather hard to encounter cases where such levels of isolation are necessary. Most of the time you want to start with either REPEATABLE READ or SERIALIZABLE.