I have configured hibernate to use oracle sequence. Sequence is created with cache=20, increment=1.

All works fine, hibernate persisting entities. The id value is strange: 50,51....76,201,202...209,1008,1009,5129,5130 ....

If I ask for sequence value (select hibernate_sequence.nextval from dual) I get value like 2,3,4 ....

If I turn on hibernate sql debug, there is time to time call "select hibernate_sequence.nextval from dual" but number assigned by hibernate to ID doesn't relay on sequence!

Add allocationSize=1 to your @SequenceGenerator


The problem stems from a strange default value in JPA allocationSize=50, in fact it's for performance reasons.

Thank you, it works.

Explanation is there: http://stackoverflow.com/questions/7171626/hibernate-with-oracle-sequence-doesnt-use-it