lidavidm commented on a change in pull request #11466:
URL: https://github.com/apache/arrow/pull/11466#discussion_r741077193
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File path: cpp/src/arrow/array/array_nested.cc
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@@ -541,56 +541,62 @@ std::shared_ptr<Array> StructArray::GetFieldByName(const
std::string& name) cons
Result<ArrayVector> StructArray::Flatten(MemoryPool* pool) const {
ArrayVector flattened;
- flattened.reserve(data_->child_data.size());
+ flattened.resize(data_->child_data.size());
std::shared_ptr<Buffer> null_bitmap = data_->buffers[0];
- for (const auto& child_data_ptr : data_->child_data) {
- auto child_data = child_data_ptr->Copy();
+ for (int i = 0; static_cast<size_t>(i) < data_->child_data.size(); i++) {
+ ARROW_ASSIGN_OR_RAISE(flattened[i], Flatten(i, pool));
+ }
- std::shared_ptr<Buffer> flattened_null_bitmap;
- int64_t flattened_null_count = kUnknownNullCount;
+ return flattened;
+}
- // Need to adjust for parent offset
- if (data_->offset != 0 || data_->length != child_data->length) {
- child_data = child_data->Slice(data_->offset, data_->length);
- }
- std::shared_ptr<Buffer> child_null_bitmap = child_data->buffers[0];
- const int64_t child_offset = child_data->offset;
-
- // The validity of a flattened datum is the logical AND of the struct
- // element's validity and the individual field element's validity.
- if (null_bitmap && child_null_bitmap) {
- ARROW_ASSIGN_OR_RAISE(
- flattened_null_bitmap,
- BitmapAnd(pool, child_null_bitmap->data(), child_offset,
null_bitmap_data_,
- data_->offset, data_->length, child_offset));
- } else if (child_null_bitmap) {
- flattened_null_bitmap = child_null_bitmap;
- flattened_null_count = child_data->null_count;
- } else if (null_bitmap) {
- if (child_offset == data_->offset) {
- flattened_null_bitmap = null_bitmap;
- } else {
- // If the child has an offset, need to synthesize a validity
- // buffer with an offset too
- ARROW_ASSIGN_OR_RAISE(flattened_null_bitmap,
- AllocateEmptyBitmap(child_offset +
data_->length, pool));
- CopyBitmap(null_bitmap_data_, data_->offset, data_->length,
- flattened_null_bitmap->mutable_data(), child_offset);
- }
- flattened_null_count = data_->null_count;
- } else {
- flattened_null_count = 0;
- }
+Result<std::shared_ptr<Array>> StructArray::Flatten(int index, MemoryPool*
pool) const {
+ std::shared_ptr<Buffer> null_bitmap = data_->buffers[0];
+
+ auto child_data = data_->child_data[index]->Copy();
Review comment:
Shallow copy.
https://github.com/apache/arrow/blob/a0c650415bc28920512077faecdfa9d07d3c4efe/cpp/src/arrow/array/data.h#L164
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