From 28e3b99414ea7ddc126b41b6cf1fc7dd2b61e23d Mon Sep 17 00:00:00 2001
From: Piotr Findeisen <piotr.findeisen@gmail.com>
Date: Fri, 22 Nov 2024 22:36:47 +0100
Subject: [PATCH] Fix panic when hashing empty FixedSizeList Array

Previously it would panic due to division by zero.
---
 datafusion/common/src/hash_utils.rs | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/datafusion/common/src/hash_utils.rs b/datafusion/common/src/hash_utils.rs
index e18d70844d32..f4cb497c5c27 100644
--- a/datafusion/common/src/hash_utils.rs
+++ b/datafusion/common/src/hash_utils.rs
@@ -322,7 +322,11 @@ 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 +458,16 @@ 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]));