RatulDawar commented on code in PR #21877:
URL: https://github.com/apache/datafusion/pull/21877#discussion_r3149506094
##########
datafusion/functions/src/unicode/substrindex.rs:
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@@ -261,30 +261,37 @@ fn visible_string_bytes<T: OffsetSizeTrait>(
offsets[offsets.len() - 1].as_usize() - offsets[0].as_usize()
}
-fn substr_index_general<'a, S, B>(
+fn substr_index_general<'a, S, O>(
string_array: S,
delimiter_array: S,
count_array: &PrimitiveArray<Int64Type>,
- mut builder: B,
+ mut builder: GenericStringArrayBuilder<O>,
) -> Result<ArrayRef>
where
S: StringArrayType<'a> + Copy,
- B: StringLikeArrayBuilder,
+ O: OffsetSizeTrait,
{
- for ((string, delimiter), n) in string_array
- .iter()
- .zip(delimiter_array.iter())
- .zip(count_array.iter())
- {
- match (string, delimiter, n) {
- (Some(string), Some(delimiter), Some(n)) => {
- builder.append_value(substr_index_slice(string, delimiter, n));
- }
- _ => builder.append_null(),
+ let num_rows = string_array.len();
+ // Output is null IFF any input is null.
+ let nulls = NullBuffer::union(
Review Comment:
Isn’t this highly dependent on heuristics—whether the cost of performing the
bitmap union is actually justified by the append_nulls operations it helps us
avoid?
Especially since the other approach of 1 by 1 scanning rows is also
sequential IO ?
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