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Type: Improvement Improvement
Status: Closed Closed
Resolution: Fixed
Priority: Major Major
Assignee: Unassigned
Reporter: Andy Jefferson
Votes: 0
Watchers: 0

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DataNucleus Store RDBMS

Should allow M-N ordered lists but currently dont

Created: 20/Dec/13 12:39 PM   Updated: 21/Dec/13 11:37 AM   Resolved: 20/Dec/13 04:01 PM
Component/s: ORM
Affects Version/s: None
Fix Version/s: 3.2.10

 Description  « Hide
We currently only support M-N relations for Sets since lists were traditionally indexed only (and it makes no sense at all to have a M-N indexed list relation, since there would have to be 2 indexes in the join table, and inserting would be a nightmare to set both index positions). In principle an ordered List should be usable as an M-N relation. The problem with this currently is that JoinListStore has no logic to not persist duplicates (one from each side) whereas JoinSetStore does have some logic for this.

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Andy Jefferson added a comment - 20/Dec/13 04:01 PM
GitHub master has code to prevent dups in ordered lists by only persisting from the owner side of the M-N. Simple test added to GutHub, and outline docs added.