Increasing persistency performance. Now that we don't rely on the sequence generators during mass data storage, the insert query doesn't have to return the generated id (since we supply it). This gets rid of some data flow, and also some extra work because of a Hibernate stupidity: it returns back PostgreSQL bigint data type values as java.math.BigInteger (see http://oreilly.com/java/excerpts/harnessing-hibernate/hibernate-types.html), although Hibernate bigint is an 8 byte integer which would correspond to a long in Java. So we avoid that now for mass data storages.