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ARROW-14741: [C++] Add support for RecordBatchReader in CSV writer #11899

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ARROW-14741: [C++] Add support for RecordBatchReader in CSV writer #11899

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53d787e
Add support for RecordBatchReader in CSV writer
ahadnagy Dec 8, 2021
3db5f57
Small refactor
ahadnagy Dec 8, 2021
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14 changes: 13 additions & 1 deletion cpp/src/arrow/csv/writer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -192,7 +192,7 @@ class UnquotedColumnPopulator : public ColumnPopulator {
return VisitArrayDataInline<StringType>(
*casted_array_->data(),
[&](arrow::util::string_view s) {
ARROW_RETURN_NOT_OK(CheckStringHasNoStructuralChars(s));
RETURN_NOT_OK(CheckStringHasNoStructuralChars(s));
return valid_function(s);
},
null_function);
Expand Down Expand Up @@ -548,6 +548,18 @@ Status WriteCSV(const RecordBatch& batch, const WriteOptions& options,
return writer->Close();
}

Status WriteCSV(const std::shared_ptr<RecordBatchReader>& reader,
const WriteOptions& options, arrow::io::OutputStream* output) {
ASSIGN_OR_RAISE(auto writer, MakeCSVWriter(output, reader->schema(), options));
std::shared_ptr<RecordBatch> batch;
while (true) {
ASSIGN_OR_RAISE(batch, reader->Next());
if (batch == nullptr) break;
RETURN_NOT_OK(writer->WriteRecordBatch(*batch));
}
return writer->Close();
}

ARROW_EXPORT
Result<std::shared_ptr<ipc::RecordBatchWriter>> MakeCSVWriter(
std::shared_ptr<io::OutputStream> sink, const std::shared_ptr<Schema>& schema,
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6 changes: 6 additions & 0 deletions cpp/src/arrow/csv/writer.h
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Expand Up @@ -45,6 +45,12 @@ ARROW_EXPORT Status WriteCSV(const Table& table, const WriteOptions& options,
/// Experimental
ARROW_EXPORT Status WriteCSV(const RecordBatch& batch, const WriteOptions& options,
arrow::io::OutputStream* output);
/// \brief Converts batches read through a RecordBatchReader
/// to CSV and writes the results to output.
/// Experimental
ARROW_EXPORT Status WriteCSV(const std::shared_ptr<RecordBatchReader>& reader,
const WriteOptions& options,
arrow::io::OutputStream* output);

/// \brief Create a new CSV writer. User is responsible for closing the
/// actual OutputStream.
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6 changes: 6 additions & 0 deletions cpp/src/arrow/csv/writer_test.cc
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Expand Up @@ -259,6 +259,12 @@ TEST_P(TestWriteCSV, TestWrite) {
ASSERT_OK_AND_ASSIGN(csv, ToCsvString(*table, options));
EXPECT_EQ(csv, GetParam().expected_output);

// RecordBatchReader should work identically.
ASSERT_OK_AND_ASSIGN(std::shared_ptr<RecordBatchReader> reader,
RecordBatchReader::Make({record_batch}));
ASSERT_OK_AND_ASSIGN(csv, ToCsvString(reader, options));
EXPECT_EQ(csv, GetParam().expected_output);

// The writer should work identically.
ASSERT_OK_AND_ASSIGN(csv, ToCsvStringUsingWriter(*table, options));
EXPECT_EQ(csv, GetParam().expected_output);
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