From b74a0621bb1e10cc52ecfd2d0fa051e0045531f5 Mon Sep 17 00:00:00 2001
From: Jagdish Parihar <jatin6972@gmail.com>
Date: Wed, 8 Jan 2025 21:01:16 +0530
Subject: [PATCH] for 'array_repeat' if the count value is 0, return NULL
 instead of empty array

---
 datafusion/functions-nested/src/repeat.rs    | 22 +++++++++++++++++---
 datafusion/sqllogictest/test_files/array.slt |  6 +++---
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/datafusion/functions-nested/src/repeat.rs b/datafusion/functions-nested/src/repeat.rs
index da0aa5f12fde..6974499c54b0 100644
--- a/datafusion/functions-nested/src/repeat.rs
+++ b/datafusion/functions-nested/src/repeat.rs
@@ -24,7 +24,7 @@ use arrow_array::{
     new_null_array, Array, ArrayRef, GenericListArray, Int64Array, ListArray,
     OffsetSizeTrait,
 };
-use arrow_buffer::OffsetBuffer;
+use arrow_buffer::{BooleanBufferBuilder, OffsetBuffer};
 use arrow_schema::DataType::{LargeList, List};
 use arrow_schema::{DataType, Field};
 use datafusion_common::cast::{as_int64_array, as_large_list_array, as_list_array};
@@ -169,6 +169,7 @@ fn general_repeat<O: OffsetSizeTrait>(
 ) -> Result<ArrayRef> {
     let data_type = array.data_type();
     let mut new_values = vec![];
+    let mut null_bits = BooleanBufferBuilder::new(array.len());
 
     let count_vec = count_array
         .values()
@@ -178,6 +179,13 @@ fn general_repeat<O: OffsetSizeTrait>(
         .collect::<Vec<_>>();
 
     for (row_index, &count) in count_vec.iter().enumerate() {
+        if count == 0 {
+            null_bits.append(false);
+            new_values.push(new_null_array(data_type, 0));
+            continue;
+        }
+
+        null_bits.append(true);
         let repeated_array = if array.is_null(row_index) {
             new_null_array(data_type, count)
         } else {
@@ -203,7 +211,7 @@ fn general_repeat<O: OffsetSizeTrait>(
         Arc::new(Field::new_list_field(data_type.to_owned(), true)),
         OffsetBuffer::from_lengths(count_vec),
         values,
-        None,
+        Some(null_bits.finish().into()),
     )?))
 }
 
@@ -224,6 +232,7 @@ fn general_list_repeat<O: OffsetSizeTrait>(
     let data_type = list_array.data_type();
     let value_type = list_array.value_type();
     let mut new_values = vec![];
+    let mut null_bits = BooleanBufferBuilder::new(list_array.len());
 
     let count_vec = count_array
         .values()
@@ -233,6 +242,13 @@ fn general_list_repeat<O: OffsetSizeTrait>(
         .collect::<Vec<_>>();
 
     for (list_array_row, &count) in list_array.iter().zip(count_vec.iter()) {
+        if count == 0 {
+            null_bits.append(false);
+            new_values.push(new_null_array(data_type, 0));
+            continue;
+        }
+
+        null_bits.append(true);
         let list_arr = match list_array_row {
             Some(list_array_row) => {
                 let original_data = list_array_row.to_data();
@@ -271,6 +287,6 @@ fn general_list_repeat<O: OffsetSizeTrait>(
         Arc::new(Field::new_list_field(data_type.to_owned(), true)),
         OffsetBuffer::<i32>::from_lengths(lengths),
         values,
-        None,
+        Some(null_bits.finish().into()),
     )?))
 }
diff --git a/datafusion/sqllogictest/test_files/array.slt b/datafusion/sqllogictest/test_files/array.slt
index 90003b28572a..e943db532b3e 100644
--- a/datafusion/sqllogictest/test_files/array.slt
+++ b/datafusion/sqllogictest/test_files/array.slt
@@ -2729,7 +2729,7 @@ select
   list_repeat('rust', 4),
   list_repeat(null, 0);
 ----
-[1, 1, 1, 1, 1] [3.14, 3.14, 3.14] [l, l, l, l] [, ] [-1, -1, -1, -1, -1] [] [rust, rust, rust, rust] []
+[1, 1, 1, 1, 1] [3.14, 3.14, 3.14] [l, l, l, l] [, ] [-1, -1, -1, -1, -1] NULL [rust, rust, rust, rust] NULL
 
 # array_repeat scalar function #2 (element as list)
 query ????
@@ -2783,7 +2783,7 @@ from array_repeat_table;
 [1] [1.1] [a] [[4, 5, 6]] [1, 1, 1] [[1]]
 [, ] [, ] [, ] [, ] [, , ] [[1], [1]]
 [2, 2, 2] [2.2, 2.2, 2.2] [rust, rust, rust] [[7], [7], [7]] [2, 2, 2] [[1], [1], [1]]
-[] [] [] [] [3, 3, 3] []
+NULL NULL NULL NULL [3, 3, 3] NULL
 
 query ??????
 select
@@ -2798,7 +2798,7 @@ from large_array_repeat_table;
 [1] [1.1] [a] [[4, 5, 6]] [1, 1, 1] [[1]]
 [, ] [, ] [, ] [, ] [, , ] [[1], [1]]
 [2, 2, 2] [2.2, 2.2, 2.2] [rust, rust, rust] [[7], [7], [7]] [2, 2, 2] [[1], [1], [1]]
-[] [] [] [] [3, 3, 3] []
+NULL NULL NULL NULL [3, 3, 3] NULL
 
 statement ok
 drop table array_repeat_table;