[GitHub] [arrow-datafusion] Dandandan commented on a diff in pull request #7043: Specialize single column primitive group values

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

Dandandan commented on code in PR #7043:
URL: https://github.com/apache/arrow-datafusion/pull/7043#discussion_r1270440126


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datafusion/core/src/physical_plan/aggregates/group_values/primitive.rs:
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@@ -0,0 +1,191 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use crate::physical_plan::aggregates::group_values::GroupValues;
+use ahash::RandomState;
+use arrow::array::BooleanBufferBuilder;
+use arrow::buffer::NullBuffer;
+use arrow::datatypes::i256;
+use arrow_array::cast::AsArray;
+use arrow_array::{ArrayRef, ArrowNativeTypeOp, ArrowPrimitiveType, PrimitiveArray};
+use arrow_schema::DataType;
+use datafusion_common::Result;
+use datafusion_execution::memory_pool::proxy::VecAllocExt;
+use datafusion_physical_expr::EmitTo;
+use half::f16;
+use hashbrown::raw::RawTable;
+use std::sync::Arc;
+
+/// A trait to allow hashing of floating point numbers
+trait HashValue {
+    fn hash(self, state: &RandomState) -> u64;
+}
+
+macro_rules! hash_integer {
+    ($($t:ty),+) => {
+        $(impl HashValue for $t {
+            fn hash(self, state: &RandomState) -> u64 {
+                state.hash_one(self)
+            }
+        })+
+    };
+}
+hash_integer!(i8, i16, i32, i64, i128, i256);
+hash_integer!(u8, u16, u32, u64);
+
+macro_rules! hash_float {
+    ($($t:ty),+) => {
+        $(impl HashValue for $t {
+            fn hash(self, state: &RandomState) -> u64 {
+                state.hash_one(self.to_bits())
+            }
+        })+
+    };
+}
+
+hash_float!(f16, f32, f64);
+
+/// A [`GroupValues`] storing raw primitive values
+pub struct GroupValuesPrimitive<T: ArrowPrimitiveType> {
+    /// The data type of the output array
+    data_type: DataType,
+    /// Stores the group index based on the hash of its value
+    map: RawTable<usize>,

Review Comment:
   I wonder if you tried `RawTable<(T::Native, usize)>` as well? Not sure if we could expect much benefit, maybe slightly better locality as we only have to follow one pointer.



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