[GitHub] [arrow] joeyac commented on issue #9311: [arrow c++] How can I modify `RecordBatch` or `Table` value piped from another c++ program?

[GitBox <gi...@apache.org>]

joeyac commented on issue #9311:
URL: https://github.com/apache/arrow/issues/9311#issuecomment-766898581


   finally, I found the related source code:
   https://github.com/apache/arrow/blob/master/cpp/src/arrow/io/memory.cc#L351
   before this line, `buffer_` from `StdinStream` is mutable, but `buffer` sliced by `SliceBuffer` returns an immutable `buffer` by default.
   I replace
   ```cpp
   return SliceBuffer(buffer_, position, nbytes);
   ```
   with
   ```cpp
   if (buffer_->is_mutable()) return SliceMutableBuffer(buffer_, position, nbytes);
   else return SliceBuffer(buffer_, position, nbytes);
   ```
   then I can modify data with mutable data ptr.
   


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