slt: Add test for REE arrays in group by

Author: brancz

datafusion/sqllogictest/test_files/run_end_encoded.slt

@@ -0,0 +1,57 @@
+# 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.
+
+# Tests for Run-End Encoded (REE) array support in aggregations
+# This tests that REE arrays can be used as GROUP BY keys (requires proper hashing support)
+
+# Create a table with REE-encoded sensor IDs using arrow_cast
+# First create primitive arrays, then cast to REE in a second step
+statement ok
+CREATE TABLE sensor_readings AS
+WITH raw_data AS (
+  SELECT * FROM (
+    VALUES
+      ('sensor_A', 22),
+      ('sensor_A', 23),
+      ('sensor_B', 20),
+      ('sensor_A', 24)
+  ) AS t(sensor_id, temperature)
+)
+SELECT
+  arrow_cast(sensor_id, 'RunEndEncoded("run_ends": non-null Int32, "values": Utf8)') AS sensor_id,
+  temperature
+FROM raw_data;
+
+# Test basic aggregation with REE column as GROUP BY key
+query ?RI rowsort
+SELECT
+    sensor_id,
+    AVG(temperature) AS avg_temp,
+    COUNT(*) AS reading_count
+FROM sensor_readings
+GROUP BY sensor_id;
+----
+sensor_A 23 3
+sensor_B 20 1
+
+# Test DISTINCT with REE column
+query ? rowsort
+SELECT DISTINCT sensor_id
+FROM sensor_readings;
+----
+sensor_A
+sensor_B