WL#2495: Handle diverse partition sets for scans in NDB API with read_multi_range

Status: Assigned   —   Priority: Medium

As for WL 2494 but for the special case of Read Multiple Ranges

In this case the scan is performed on all fragments but TC can
filter out which partitions to send to each fragment and in some
cases there might even be zero ranges where it isn't necessary to
scan the fragment at all.