freakyzoidberg commented on code in PR #23337:
URL: https://github.com/apache/datafusion/pull/23337#discussion_r3571282521
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datafusion/functions-nested/src/array_has.rs:
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@@ -344,6 +361,229 @@ fn array_has_dispatch_for_array<'a>(
Ok(Arc::new(BooleanArray::new(result.finish(), combined_nulls)))
}
+/// Average list length past which the element-null fast path (case 2 of
+/// [`array_has_array_primitive`]) stops beating the per-row `eq` kernel and is
+/// bailed out of -- an empirically measured crossover.
+const NULL_FAST_PATH_MAX_LEN: usize = 512;
+
+/// Per-element fast path for primitive and string element types. Returns
`None`
+/// for any other type (and on a needle/element type mismatch), so the caller
+/// falls back to the per-row `eq` kernel.
+fn array_has_array_fast_path(
+ haystack: &ArrayWrapper<'_>,
+ needle: &ArrayRef,
+ combined_nulls: Option<&NullBuffer>,
+) -> Option<BooleanBuffer> {
+ let needle = needle.as_ref();
+
+ // Normalize for sliced arrays (like `array_has_dispatch_for_scalar`):
slice
+ // to the visible region so `offsets[i] - first_offset` indexes the values.
+ let offsets: Vec<usize> = haystack.offsets().collect();
+ let first_offset = offsets[0];
+ let visible_values = haystack
+ .values()
+ .slice(first_offset, offsets[offsets.len() - 1] - first_offset);
+ let visible_values = visible_values.as_ref();
+
+ // The needle shares the haystack's element type after coercion; defer any
+ // mismatch to the generic path rather than panicking in the downcasts.
+ if visible_values.data_type() != needle.data_type() {
+ return None;
+ }
+
+ downcast_primitive_array! {
+ visible_values => {
+ // The element-null branch of `array_has_array_primitive` makes
+ // several passes over the values; past a moderate average list
+ // length the per-row `eq` kernel wins, so bail to it there.
Measured
+ // over the *visible* region -- the offset span and
`visible_values`
+ // nulls, not the full backing child -- so a sliced array's hidden
+ // elements can't skew the decision. The average check
short-circuits,
+ // so the all-valid win path never pays for `null_count`. Strings
+ // (single-pass) and nested types have no such crossover and never
+ // reach this arm.
+ let num_rows = offsets.len() - 1;
Review Comment:
as per @Jefffrey comment, simplified the comment and offset mangement to the
minimum
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