The query processing was implicitly relying on the order provided by the
catalog. This had two issues:
- this ordering was not defined in the API contract (neither via docs
nor via typing)
- the order was based on chunk IDs which is not adequate in some cases
(e.g. when chunks are created while a persistence operations is in
progress)
Now we explicitly sort chunks by `(order, ID)`.
Fixes#1963.
Marco Neumann