[C++][Java][FlightRPC] Add support for ordered data

[kou]

Describe the enhancement requested

Based on the proposal in https://docs.google.com/document/d/1jhPyPZSOo2iy0LqIJVUs9KWPyFULVFJXTILDfkadx2g/edit# .
See also the discussion thread: https://lists.apache.org/thread/247z3t06mf132nocngc1jkp3oqglz7jp

Currently, the endpoints within a FlightInfo explicitly have no ordering:

There is no ordering defined on endpoints. Hence, if the returned data has an ordering, it should be returned in a single endpoint.

This is unnecessarily limiting. Systems can and do implement distributed sorts, but they can’t reflect this in Flight RPC. And users are asking; see this Stack Overflow question.

Proposal:

Add a flag to FlightInfo:

message FlightInfo {
  // FlightEndpoints are in the same order as the data.
  bool endpoints_ordered = 6;
}

If set, the client may assume that the data is sorted in the same order as the endpoints. Otherwise, the client cannot make any assumptions (as before).

Component(s)

C++, Java,FlightRPC

[kou]

Discussion: https://lists.apache.org/thread/0q1s84p17rtdz3q81wvylckob1hsx83z