Em Mon, 09 Feb 2009 22:35:52 -0300, Luther Baker <lutherba...@gmail.com>
escreveu:
This is a little offtopic - so I apologize in advance but I'm building
Tapestry applications and have a Hibernate question that I'd like to pose
here.
Is there preferred type for simple Hibernate IDs?
I always use an artificial (i.e. a column that is used only as id, not
being used to store real data) integer column generated by the DBMS as a
table primary key. I always use Integer, unless I expect the number of
rows to be huge. In that cases, I use Long.
By the way, *never* use compound primary keys or any natural id column.
That's my advice. It's simple, it's fast, it prevents some very bad
problems when you need to change the database structure.
Simply stated, I'm asking about the two orthogonal choices: (native vs
object, range or size)
Is an int preferred to an Integer? Is there a compelling argument for
either native or Object?
I guess that you mean "primite" when you mean "native".
Native types in Java can't have null values, so, for primary key
properties, a Integer is a much better fit than an int.
Is an Integer preferred to a Long (if the extra range of the the Long is
unecessary)?
Yes.
For instance, using hsqldb - would a Long possibly require TWO columns
and an Integer only one?
No. A Long would require a 64 bits column type in the DBMS.
--
Thiago H. de Paula Figueiredo
Independent Java consultant, developer, and instructor
http://www.arsmachina.com.br/thiago
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