style: Address unused variable warnings

Author: srh

datafusion/src/physical_plan/groups_accumulator.rs

@@ -18,9 +18,7 @@
 //! Vectorized [`GroupsAccumulator`]
 
 use crate::error::{DataFusionError, Result};
-use crate::scalar::ScalarValue;
 use arrow::array::{ArrayRef, BooleanArray};
-use smallvec::SmallVec;
 
 /// From upstream:  This replaces a datafusion_common::{not_impl_err} import.
 macro_rules! not_impl_err {

datafusion/src/physical_plan/groups_accumulator_adapter.rs

@@ -33,7 +33,6 @@ use arrow::{
     compute,
     datatypes::UInt32Type,
 };
-use smallvec::SmallVec;
 
 /// An adapter that implements [`GroupsAccumulator`] for any [`Accumulator`]
 ///

datafusion/src/physical_plan/groups_accumulator_prim_op.rs

@@ -15,6 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
+//! PrimitiveGroupsAccumulator
+
 use std::any::type_name;
 use std::marker::PhantomData;
 use std::mem::size_of;

datafusion/src/physical_plan/hash_aggregate.rs

@@ -1174,8 +1174,6 @@ pub(crate) fn create_batch_from_map(
     // 4. collect all in a vector per key of vec<ArrayRef>, vec[i][j]
     // 5. concatenate the arrays over the second index [j] into a single vec<ArrayRef>.
 
-    let mut key_columns: Vec<Box<dyn ArrayBuilder>> = Vec::with_capacity(num_group_expr);
-
     let key_columns: Vec<Box<dyn ArrayBuilder>> = write_group_result_rows_for_keys(
         &accumulation_state.flattened_group_by_values,
         accumulation_state.next_group_index,