[
https://issues.apache.org/jira/browse/ARROW-2119?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16358997#comment-16358997
]
Wes McKinney commented on ARROW-2119:
-------------------------------------
I believe we should make some changes to support streams having a schema but no
record batches. In C++ / Python, if there are none, then
{{Table::FromRecordBatches}} should not be called
> Handle Arrow stream with zero record batch
> ------------------------------------------
>
> Key: ARROW-2119
> URL: https://issues.apache.org/jira/browse/ARROW-2119
> Project: Apache Arrow
> Issue Type: Bug
> Reporter: Jingyuan Wang
> Priority: Major
>
> It looks like currently many places of the code assume that there needs to be
> at least one record batch for streaming format. Is zero-recordbatch not
> supported by design?
> e.g.
> [https://github.com/apache/arrow/blob/master/java/tools/src/main/java/org/apache/arrow/tools/StreamToFile.java#L45]
> {code:none}
> public static void convert(InputStream in, OutputStream out) throws
> IOException {
> BufferAllocator allocator = new RootAllocator(Integer.MAX_VALUE);
> try (ArrowStreamReader reader = new ArrowStreamReader(in, allocator)) {
> VectorSchemaRoot root = reader.getVectorSchemaRoot();
> // load the first batch before instantiating the writer so that we have
> any dictionaries
> if (!reader.loadNextBatch()) {
> throw new IOException("Unable to read first record batch");
> }
> ...
> {code}
> Pyarrow-0.8.0 does not load 0-recordbatch stream either. It would throw an
> exception originated from
> [https://github.com/apache/arrow/blob/a95465b8ce7a32feeaae3e13d0a64102ffa590d9/cpp/src/arrow/table.cc#L309:]
> {code:none}
> Status Table::FromRecordBatches(const
> std::vector<std::shared_ptr<RecordBatch>>& batches,
> std::shared_ptr<Table>* table) {
> if (batches.size() == 0) {
> return Status::Invalid("Must pass at least one record batch");
> }
> ...{code}
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
