Hi,
I've found that when I serialize two recordbatches which have a
dictionary-encoded field, but different encoding dictionaries to a sequence of
pybytes with a RecordBatchStreamWriter, then deserialize using
pa.ipc.open_stream(), the dictionaries get jumbled. (or at least, on
deserialization, the dictionary for the first RB is being reused for the second)
MWE:
```
import pyarrow as pa
from io import BytesIO
pa.__version__
schema = pa.schema([pa.field('foo', pa.int32()), pa.field('bar',
pa.dictionary(pa.int32(), pa.string()))] )
r1 = pa.record_batch(
[
[1, 2, 3, 4, 5],
pa.array(["a", "b", "c", "d", "e"]).dictionary_encode()
],
schema
)
r1.validate()
r2 = pa.record_batch(
[
[1, 2, 3, 4, 5],
pa.array(["c", "c", "e", "f", "g"]).dictionary_encode()
],
schema
)
r2.validate()
assert r1.column(1).dictionary != r2.column(1).dictionary
sink = pa.BufferOutputStream()
writer = pa.RecordBatchStreamWriter(sink, schema)
writer.write(r1)
writer.write(r2)
serialized = BytesIO(sink.getvalue().to_pybytes())
stream = pa.ipc.open_stream(serialized)
deserialized = []
while True:
try:
deserialized.append(stream.read_next_batch())
except StopIteration:
break
deserialized[0].column(1).to_pylist()
deserialized[1].column(1).to_pylist()
```
(The last line of the above prints out `['a', 'a', 'b', 'c', 'd']`. This
behaviour doesn't look right. I was wondering whether I'm simply not using the
library correctly or if this is a bug in pyarrow.
Thanks,
Al
