XiangpengHao commented on code in PR #5871:
URL: https://github.com/apache/arrow-rs/pull/5871#discussion_r1635357225
##########
arrow-cast/src/cast/dictionary.rs:
##########
@@ -85,10 +85,97 @@ pub(crate) fn dictionary_cast<K: ArrowDictionaryKeyType>(
Ok(new_array)
}
+ Utf8View => {
+ // `unpack_dictionary` can handle Utf8View/BinaryView types, but
incurs unnecessary data copy of the value buffer.
+ // we handle it here to avoid the copy.
+ let dict_array = array
+ .as_dictionary::<K>()
+ .downcast_dict::<StringArray>()
+ .unwrap();
+
+ let string_values = dict_array.values();
+ let value_offsets = string_values.value_offsets();
+ let value_buffer = string_values.values().clone();
+
+ let view_buffer =
+ view_from_dict_values(value_offsets, &value_buffer,
dict_array.keys());
+
+ // Safety:
+ // the buffer is from StringArray which is utf8.
+ let string_view = unsafe {
+ StringViewArray::new_unchecked(
+ view_buffer,
+ vec![value_buffer],
+ dict_array.nulls().cloned(),
Review Comment:
added now!
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