more unsafe according to flamegraph.

Author: Rachelint

datafusion/functions-aggregate-common/src/aggregate/groups_accumulator/blocks.rs

@@ -162,14 +162,18 @@ impl<B: Block> Index<usize> for Blocks<B> {
 
     #[inline]
     fn index(&self, index: usize) -> &Self::Output {
-        &self.inner[index]
+        unsafe {
+            self.inner.get_unchecked(index)
+        }
     }
 }
 
 impl<B: Block> IndexMut<usize> for Blocks<B> {
     #[inline]
     fn index_mut(&mut self, index: usize) -> &mut Self::Output {
-        &mut self.inner[index]
+        unsafe {
+            self.inner.get_unchecked_mut(index)
+        }
     }
 }