It seems that the array_union_test.cc does the latter, look at how `expected_types` is constructed. I opened https://issues.apache.org/jira/browse/ARROW-7265 .
Wes, is the intended usage of type_ids to allow a producer to pass a subset columns of unions without modifying the type codes? François On Thu, Nov 21, 2019 at 10:51 AM Antoine Pitrou <anto...@python.org> wrote: > > > Hello, > > There's some ambiguity whether a union array's "types" buffer stores > physical child ids, or logical type codes. > > Some of our C++ tests assume the former: > https://github.com/apache/arrow/blob/master/cpp/src/arrow/array_union_test.cc#L107-L123 > > Some of our C++ tests assume the latter: > https://github.com/apache/arrow/blob/master/cpp/src/arrow/array_union_test.cc#L311-L326 > https://github.com/apache/arrow/blob/master/cpp/src/arrow/ipc/json_simple_test.cc#L943-L955 > > Critically, no validation of union data is currently implemented in C++ > (ARROW-6157). I can't parse the Java source code. > > Regards > > Antoine. >
