[GitHub] [arrow-rs] tustvold commented on a diff in pull request #2048: Improve `validate_utf8` performance

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

tustvold commented on code in PR #2048:
URL: https://github.com/apache/arrow-rs/pull/2048#discussion_r928123907


##########
arrow/src/array/data.rs:
##########
@@ -1125,16 +1125,37 @@ impl ArrayData {
         T: ArrowNativeType + TryInto<usize> + num::Num + std::fmt::Display,
     {
         let values_buffer = &self.buffers[1].as_slice();
-
-        self.validate_each_offset::<T, _>(values_buffer.len(), |string_index, range| {
-            std::str::from_utf8(&values_buffer[range.clone()]).map_err(|e| {
-                ArrowError::InvalidArgumentError(format!(
-                    "Invalid UTF8 sequence at string index {} ({:?}): {}",
-                    string_index, range, e
-                ))
-            })?;
-            Ok(())
-        })
+        if let Ok(values_str) = std::str::from_utf8(values_buffer) {
+            // Validate Offsets are correct
+            self.validate_each_offset::<T, _>(
+                values_buffer.len(),
+                |string_index, range| {
+                    if !values_str.is_char_boundary(range.start)
+                        || !values_str.is_char_boundary(range.end)

Review Comment:
   I think you can remove `values_str.is_char_boundary(range.end)`, as the end offset is the start offset of the next string slice. We do not need to check the final offset as if the end of the string is not a valid char boundary, the string as a whole would fail validation.



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