Schema evolution: Item addition based on projections

[fjavierm]

Context

'Item addition' operation defined as an addition of the item projection can cause unexpected results that maybe deserve further consideration.

• RFC code: 0001-schema-evolution-field-operations

Explanation

The RFC for schema evolution defines the 'Item addition' operation as an addition of the item projection, this can cause that external or internal systems can continue providing values for fields that are not consider any more due they are not in the projection (not considered for validation nor for storage).

• Should we make these systems aware of the situation?
• Should we consider to have presentation (read) lens and working (write) lens?
• What happen if the field is not in the projection just for a period of time? Some updates can be missed during the time the field is not in the projection and, when the field is there again, some unexpected values for this field can show.

[arnau]

Nice one 👍

Related to #1