Talk:EclipseLink/DesignDocs/340192

The EXTENSION_DEF has no way of matching rows to fields in the Customer table.

EXTENSION_DEF requires a field to store the referenced field name (in the flexfield case). This allows custom naming to be used, and ensures the EXTENSION_DEF rows match up consistently to the same fields. It also makes the sequence id field unnecessary, as the ENT_NAME and this fieldName reference would uniquely identify it.

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ExtensionProperties will also need a way to represent multiple fields - such as a 1:1 to an entity with composite foreign keys. Either the ExtensionProperty will need to represent multiple rows in the EXTENSION_DEF table, to be more along the lines of what a mapping is in EclipseLink, or addExtension potentially result in creating multiple ExtensionProperties.

If an extension has multiple ExtensionProperties, this can easily be contained in a map keyed on the extension name, with a collection of ExtensionProperties as the value.