Support entity inheritance via "extension" tables

[Tapac]

Allow to implement inheritance in something like:

object BaseTable : IdTable()
object ExtendTable : IdTable() {
   val parent = reference(BaseTable)
}

class ExtendEntity : Entity {
   val field1 by BaseTable.field1
   val field2 by ExtendTable .field2
   val dependsOnTable = BaseTable innerJoin ExtendTable
...
}

[grv87]

How ids are propagated from BaseTable to ExtendTable? Does it depend on the order of innerJoin arguments? What if I need several base tables (one for each interface/superclass)?

How this would work when another table references BaseTable? The code doesn't know whether it is ExtendEntity or Extend2Entity.
In my experience, BaseTable has enum column specifying concrete type.