Well I'm not sure if I'm entirely awake but I can of course just use the auto generated id column for the order. I am interested in an answer to my question about high precision timestamps but it is not very important.
Henno -----Oorspronkelijk bericht----- Van: Henno Vermeulen [mailto:[email protected]] Verzonden: dinsdag 3 mei 2011 12:00 Aan: '[email protected]' Onderwerp: RE: keeping construction order by using a Date or Timestamp field Oops... a version column will never work in this case anyway because it is used for single entities, not over all entities. I assume OpenJPA can internally create a Timestamp using System.nanoTime(). Is there a way to reuse this code to create my own Timestamps with the precision I want? Henno -----Oorspronkelijk bericht----- Van: Henno Vermeulen [mailto:[email protected]] Verzonden: dinsdag 3 mei 2011 11:55 Aan: '[email protected]' Onderwerp: keeping construction order by using a Date or Timestamp field Is there a way to set a date/time field to the current time so that selecting entities ordered by this field will retain the real construction (not necessarily insertion) order? So ideally it would be a function that creates Timestamps and is guaranteed to return a larger Timestamp if you call it right after creating a Timestamp. But I can't find such a TimeStamp constructor. I know something like that must exist internally for version columns in OpenJPA, but my AbstractEntity class already has a version field of type Long which I don't really want to change. What I tried was this: @Temporal(TemporalType.TIMESTAMP) @Column(nullable = false) private Date creationTime; When I do creationTime = new Date() in my constructor I get this when creating and persisting 10 entities: 2011-05-03 11:22:53.8700000 2011-05-03 11:22:53.8700000 2011-05-03 11:22:53.8800000 2011-05-03 11:22:53.8800000 2011-05-03 11:22:53.8800000 2011-05-03 11:22:53.8900000 2011-05-03 11:22:53.8900000 2011-05-03 11:22:53.9000000 2011-05-03 11:22:53.9000000 2011-05-03 11:22:53.9100000 This is not really accurate enough to guarantee the order. Regards, Henno Vermeulen Huize Molenaar
