[JDO-660] Ability to specify positioning of field 'column(s)' in datastore "table"

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: JDO 3.1-rc1
• Component/s: api, specification, tck
• Assignee: Craig L Russell
• Reporter: Andy Jefferson
• Created: 10/Jun/10 06:35
• Updated: 12/Jun/15 12:50
• Resolved: 19/Oct/12 16:18

Description

With an RDBMS datastore, when generating the schema, it is desirable to be able to specify the positioning of the column(s) of a field in the generated table.
With spreadsheet documents, it is critical to be able to define which column number is used for a particular field.
With other datastores it is also likely desirable.

To achieve this I propose adding an attribute to the XML <column> called "position". Similarly for the @Column annotation.
This can take integer values with 0-origin.

Complications :
1. how this is handled when we have inheritance. If a root class has subclass-table inheritance, then those fields are persisted into the tables of all subclasses, and we may want to override the positions for those individually - to that end the user can override the metadata of the superclass fields.
2. anything else ?