RatulDawar commented on code in PR #21877:
URL: https://github.com/apache/datafusion/pull/21877#discussion_r3149769578
##########
datafusion/functions/src/unicode/substrindex.rs:
##########
@@ -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:
> * in the bulk-NULL builder does not need to touch the NULL bitmap for
every row, whereas in the Arrow builder it does. That means fewer per-row
branches and also less data cache pressure.
Makes sense, I can go ahead and draw a conclusion from this that in many
cases, we can isolate simpler / coupled operations for better cache locality
and SIMD.
Thanks for the explanation here @neilconway
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