Specialize single column primitive group values (#7043)

* Specialize primitive group values

* Split module

* RawTable

* Support all primitives

* Add docs

* Update datafusion-cli cargo lock

* Make Cargo.toml order 'just so'

* Review feedback

---------

Co-authored-by: Andrew Lamb <[email protected]>

Author: tustvold

datafusion-cli/Cargo.lock

@@ -71,6 +71,7 @@ datafusion-sql = { path = "../sql", version = "27.0.0" }
 flate2 = { version = "1.0.24", optional = true }
 futures = "0.3"
 glob = "0.3.0"
+half = { version = "2.1", default-features = false }
 hashbrown = { version = "0.14", features = ["raw"] }
 indexmap = "2.0.0"
 itertools = "0.11"

datafusion/core/Cargo.toml

@@ -0,0 +1,64 @@
+// 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 arrow_array::{downcast_primitive, ArrayRef};
+use arrow_schema::SchemaRef;
+use datafusion_common::Result;
+use datafusion_physical_expr::EmitTo;
+
+mod primitive;
+use primitive::GroupValuesPrimitive;
+
+mod row;
+use row::GroupValuesRows;
+
+/// An interning store for group keys
+pub trait GroupValues: Send {
+    /// Calculates the `groups` for each input row of `cols`
+    fn intern(&mut self, cols: &[ArrayRef], groups: &mut Vec<usize>) -> Result<()>;
+
+    /// Returns the number of bytes used by this [`GroupValues`]
+    fn size(&self) -> usize;
+
+    /// Returns true if this [`GroupValues`] is empty
+    fn is_empty(&self) -> bool;
+
+    /// The number of values stored in this [`GroupValues`]
+    fn len(&self) -> usize;
+
+    /// Emits the group values
+    fn emit(&mut self, emit_to: EmitTo) -> Result<Vec<ArrayRef>>;
+}
+
+pub fn new_group_values(schema: SchemaRef) -> Result<Box<dyn GroupValues>> {
+    if schema.fields.len() == 1 {
+        let d = schema.fields[0].data_type();
+
+        macro_rules! downcast_helper {
+            ($t:ty, $d:ident) => {
+                return Ok(Box::new(GroupValuesPrimitive::<$t>::new($d.clone())))
+            };
+        }
+
+        downcast_primitive! {
+            d => (downcast_helper, d),
+            _ => {}
+        }
+    }
+
+    Ok(Box::new(GroupValuesRows::try_new(schema)?))
+}