Sorting OpenERP table by functional field
The reason for storing the field is that you delegate sorting to sql, that gives you more performance than any other subsequent sorting, for sure.
On search screens, users can sort the results by clicking on a column header. Unfortunately, this doesn't work for all columns. It works fine for regular fields like name and price that are stored on the table itself. It also works for many-to-one fields by joining to the referenced table and using the default sort order for that table.
What doesn't work is most functional fields and related fields. (Related fields are a type of functional field.) When you click on the column, it just ignores you. If you change the field definition to be stored in the database, then you can sort by it, but is that necessary? Is there any way to sort by a functional field without storing its values in the database?