Fix panic when hashing empty FixedSizeList Array

Previously it would panic due to division by zero.

Author: findepi

datafusion/common/src/hash_utils.rs

@@ -322,7 +322,7 @@ fn hash_fixed_list_array(
 ) -> Result<()> {
     let values = Arc::clone(array.values());
     let value_len = array.value_length();
-    let offset_size = value_len as usize / array.len();
+    let offset_size = if array.len() == 0 { 0 } else { value_len as usize / array.len() };
     let nulls = array.nulls();
     let mut values_hashes = vec![0u64; values.len()];
     create_hashes(&[values], random_state, &mut values_hashes)?;
@@ -454,6 +454,20 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn create_hashes_for_empty_fixed_size_lit() -> Result<()> {
+        let empty_array = FixedSizeListBuilder::new(StringBuilder::new(), 1).finish();
+        let random_state = RandomState::with_seeds(0, 0, 0, 0);
+        let hashes_buff = &mut vec![0; 0];
+        let hashes = create_hashes(
+            &[Arc::new(empty_array)],
+            &random_state,
+            hashes_buff,
+        )?;
+        assert_eq!(hashes, &Vec::<u64>::new());
+        Ok(())
+    }
+
     #[test]
     fn create_hashes_for_float_arrays() -> Result<()> {
         let f32_arr = Arc::new(Float32Array::from(vec![0.12, 0.5, 1f32, 444.7]));