[GitHub] [arrow-rs] tustvold commented on a diff in pull request #3622: feat: take kernel for RunArray

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

tustvold commented on code in PR #3622:
URL: https://github.com/apache/arrow-rs/pull/3622#discussion_r1089824326


##########
arrow-select/src/take.rs:
##########
@@ -810,6 +816,70 @@ where
     Ok(DictionaryArray::<T>::from(data))
 }
 
+macro_rules! primitive_run_take {
+    ($t:ty, $o:ty, $indices:ident, $value:ident) => {
+        take_primitive_run_values::<$o, $t>(
+            $indices,
+            as_primitive_array::<$t>($value.values()),
+        )
+    };
+}
+
+/// `take` implementation for run arrays
+///
+/// performs binary search on `run_ends` to get physical indices for the given logical indices.
+/// builds output run array by taking values in the input run array at the physical indices.
+/// for e.g. an input `RunArray{ run_ends = [2,4,6,8], values=[1,2,1,2] }` and `indices=[2,7]`
+/// would be converted to `physical_indices=[1,3]` which will be used to build
+/// output `RunArray{ run_ends=[2], values=[2] }`
+
+pub fn take_run<T, I>(

Review Comment:
   This is paramaterised on both the run end and the value type which is catastrophic for codegen, we **cannot** do this.
   
   How about computing the set of value indices based on the run ends and a new set of run ends, and then passing the value indices off to the normal take kernel?



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