mapleFU commented on code in PR #44822:
URL: https://github.com/apache/arrow/pull/44822#discussion_r1878168755
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cpp/src/arrow/compute/kernels/scalar_cast_string.cc:
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@@ -327,31 +329,49 @@ BinaryToBinaryCastExec(KernelContext* ctx, const
ExecSpan& batch, ExecResult* ou
}
}
+ ArrayData* output = out->array_data().get();
+ output->length = input.length;
+ output->SetNullCount(input.null_count);
+
+ // Set up validity bitmap
+ if (input.offset == output->offset) {
+ output->buffers[0] = input.GetBuffer(0);
+ } else {
+ // When the offsets are different (e.g., due to slice operation), we need
to check if
+ // the null bitmap buffer is not null before copying it. The null bitmap
buffer can be
+ // null if the input array value does not contain any null value.
+ if (input.buffers[0].data != NULLPTR) {
+ ARROW_ASSIGN_OR_RAISE(
+ output->buffers[0],
+ arrow::internal::CopyBitmap(ctx->memory_pool(),
input.buffers[0].data,
+ input.offset, input.length));
+ }
+ }
+
+ // Set up offset and data buffer
+ OffsetBuilder offset_builder(ctx->memory_pool());
+ RETURN_NOT_OK(offset_builder.Reserve(batch.length + 1));
+ offset_builder.UnsafeAppend(0); // offsets start at 0
const int64_t sum_of_binary_view_sizes = util::SumOfBinaryViewSizes(
input.GetValues<BinaryViewType::c_type>(1), input.length);
-
- // TODO(GH-43573): A more efficient implementation that copies the validity
- // bitmap all at once is possible, but would mean we don't delegate all the
- // building logic to the ArrayBuilder implementation for the output type.
- OutputBuilderType builder(options.to_type.GetSharedPtr(),
ctx->memory_pool());
- RETURN_NOT_OK(builder.Resize(input.length));
- RETURN_NOT_OK(builder.ReserveData(sum_of_binary_view_sizes));
- arrow::internal::ArraySpanInlineVisitor<I> visitor;
- RETURN_NOT_OK(visitor.VisitStatus(
- input,
- [&](std::string_view v) {
- // Append valid string view
- return builder.Append(v);
+ DataBuilder data_builder(ctx->memory_pool());
+ RETURN_NOT_OK(data_builder.Reserve(sum_of_binary_view_sizes));
+ RETURN_NOT_OK(VisitArraySpanInline<I>(
+ batch[0].array,
+ [&](std::string_view s) {
+ // for non-null value, append string view to buffer and calculate
offset
Review Comment:
what does calculate offset means?
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