[JDO-463] Clarify the behavior of an ordering column mapped to a user-visible field in the target class

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: JDO 2 maintenance release 1 (2.1)
• Fix Version/s: JDO 2 maintenance release 2 (2.2)
• Component/s: specification
• Assignee: Craig L Russell
• Reporter: Craig L Russell
• Created: 13/Feb/07 19:46
• Updated: 14/Jun/10 11:09
• Resolved: 26/Sep/08 16:21

Description

Section 18.15.8 says
<spec>
If the array or list field is mapped using the mapped-by attribute in the
field metadata, then the ordering can be mapped to a field in the same class.
In this case, use the mapped-by attribute in the order metadata to name the
field containing the ordering data.
</spec>

This doesn't say whether the List is operated as an "indexed List" (where the
JDO implementation will insert element index positions into the column
defined by the mapped-by field in the element table - and that this mapped-by
field should hence be integer based so it can store these indices), or
whether it will be an "ordered List" (like JPA, where the elements in the
List are retrieved using the ordering defined by the mapped-by column) and
the values defined by the element objects in that field will govern the
position in the list on retrieval.

Andy's (JPOX) interpretation has always been the first one, since if the user has taken
the time to insert elements into their List in an order then when they
retrieve the List they should be in the same order.