Page History

...

If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.

PartitionCount is inconsistent because it takes a number of partitions, but only assignments for the new partitions. One is absolute and the other is a difference. The reasons for this are:

• PartitionCount could take an increment, rather than the new "absolute" number of partitions. But this makes the request non-idempotent, with consequent possibilities of a double increment. This would be particularly bad because it's not possible to decrease the partition count.
• PartitionCount could take a complete assignment for both old and new partitions. This would incorrectly suggest that the request could increase the number of partitions and effect a reassignment of the existing partitions at the same time. The server would have to either ignore the old partitions (in which case why were they required to be provided?) or validate them (in which case the client has to know the old assignment in order to add more, which is needlessly difficult).