[GitHub] [arrow-rs] tustvold commented on a diff in pull request #4210: feat: Support bitwise and boolean aggregate functions

["tustvold (via GitHub)" <gi...@apache.org>]

tustvold commented on code in PR #4210:
URL: https://github.com/apache/arrow-rs/pull/4210#discussion_r1198071904


##########
arrow-arith/src/aggregate.rs:
##########
@@ -326,6 +327,115 @@ where
     }
 }
 
+macro_rules! bit_operation {
+    ($NAME:ident, $OP:ident, $NATIVE:ident, $DEFAULT:expr, $DOC:expr) => {
+        #[doc = $DOC]
+        ///
+        /// Returns `None` if the array is empty or only contains null values.
+        pub fn $NAME<T>(array: &PrimitiveArray<T>) -> Option<T::Native>
+        where
+            T: ArrowNumericType,
+            T::Native: $NATIVE<Output = T::Native> + ArrowNativeTypeOp,
+        {
+            let default;
+            if $DEFAULT == -1 {
+                default = T::Native::ONE.neg_wrapping();
+            } else {
+                default = T::default_value();
+            }
+
+            let null_count = array.null_count();
+
+            if null_count == array.len() {
+                return None;
+            }
+
+            let data: &[T::Native] = array.values();
+
+            match array.nulls() {
+                None => {
+                    let result = data
+                        .iter()
+                        .fold(default, |accumulator, value| accumulator.$OP(*value));
+
+                    Some(result)
+                }
+                Some(nulls) => {
+                    let mut result = default;
+                    let data_chunks = data.chunks_exact(64);
+                    let remainder = data_chunks.remainder();
+
+                    let bit_chunks = nulls.inner().bit_chunks();

Review Comment:
   FWIW [try_for_each_valid_idx](https://docs.rs/arrow-buffer/latest/arrow_buffer/buffer/struct.NullBuffer.html#method.try_for_each_valid_idx) may be faster for sparse arrays as it uses the CLZ to quickly skip over unset bits.
   
   It would also be less code.



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