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docs: clarify NULL handling for array_remove functions (#21014) #21018

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a846f65
docs: clarify NULL handling for array_remove functions (#21014)
Xavrir Mar 18, 2026
0b3ea0f
Merge branch 'main' into docs/issue-21014-array-null-handling
Xavrir Mar 18, 2026
38fa468
docs: trim duplicated tests from array_remove docs PR
Xavrir Mar 18, 2026
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35 changes: 28 additions & 7 deletions datafusion/functions-nested/src/remove.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,13 +40,13 @@ make_udf_expr_and_func!(
ArrayRemove,
array_remove,
array element,
"removes the first element from the array equal to the given value.",
"removes the first element from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.",
array_remove_udf
);

#[user_doc(
doc_section(label = "Array Functions"),
description = "Removes the first element from the array equal to the given value.",
description = "Removes the first element from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.",
syntax_example = "array_remove(array, element)",
sql_example = r#"```sql
> select array_remove([1, 2, 2, 3, 2, 1, 4], 2);
Expand All @@ -55,6 +55,13 @@ make_udf_expr_and_func!(
+----------------------------------------------+
| [1, 2, 3, 2, 1, 4] |
+----------------------------------------------+

> select array_remove([1, 2, NULL, 2, 4], 2);
+---------------------------------------------------+
| array_remove(List([1,2,NULL,2,4]),Int64(2)) |
+---------------------------------------------------+
| [1, NULL, 2, 4] |
+---------------------------------------------------+
```"#,
argument(
name = "array",
Expand Down Expand Up @@ -130,21 +137,28 @@ make_udf_expr_and_func!(
ArrayRemoveN,
array_remove_n,
array element max,
"removes the first `max` elements from the array equal to the given value.",
"removes the first `max` elements from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.",
array_remove_n_udf
);

#[user_doc(
doc_section(label = "Array Functions"),
description = "Removes the first `max` elements from the array equal to the given value.",
syntax_example = "array_remove_n(array, element, max))",
description = "Removes the first `max` elements from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.",
syntax_example = "array_remove_n(array, element, max)",
sql_example = r#"```sql
> select array_remove_n([1, 2, 2, 3, 2, 1, 4], 2, 2);
+---------------------------------------------------------+
| array_remove_n(List([1,2,2,3,2,1,4]),Int64(2),Int64(2)) |
+---------------------------------------------------------+
| [1, 3, 2, 1, 4] |
+---------------------------------------------------------+

> select array_remove_n([1, 2, NULL, 2, 4], 2, 2);
+----------------------------------------------------------+
| array_remove_n(List([1,2,NULL,2,4]),Int64(2),Int64(2)) |
+----------------------------------------------------------+
| [1, NULL, 4] |
+----------------------------------------------------------+
```"#,
argument(
name = "array",
Expand Down Expand Up @@ -225,13 +239,13 @@ make_udf_expr_and_func!(
ArrayRemoveAll,
array_remove_all,
array element,
"removes all elements from the array equal to the given value.",
"removes all elements from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.",
array_remove_all_udf
);

#[user_doc(
doc_section(label = "Array Functions"),
description = "Removes all elements from the array equal to the given value.",
description = "Removes all elements from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.",
syntax_example = "array_remove_all(array, element)",
sql_example = r#"```sql
> select array_remove_all([1, 2, 2, 3, 2, 1, 4], 2);
Expand All @@ -240,6 +254,13 @@ make_udf_expr_and_func!(
+--------------------------------------------------+
| [1, 3, 1, 4] |
+--------------------------------------------------+

> select array_remove_all([1, 2, NULL, 2, 4], 2);
+-----------------------------------------------------+
| array_remove_all(List([1,2,NULL,2,4]),Int64(2)) |
+-----------------------------------------------------+
| [1, NULL, 4] |
+-----------------------------------------------------+
```"#,
argument(
name = "array",
Expand Down
6 changes: 3 additions & 3 deletions docs/source/user-guide/expressions.md
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Original file line number Diff line number Diff line change
Expand Up @@ -230,9 +230,9 @@ select log(-1), log(0), sqrt(-1);
| array_positions(array, element) | Searches for an element in the array, returns all occurrences. `array_positions([1, 2, 2, 3, 4], 2) -> [2, 3]` |
| array_prepend(element, array) | Prepends an element to the beginning of an array. `array_prepend(1, [2, 3, 4]) -> [1, 2, 3, 4]` |
| array_repeat(element, count) | Returns an array containing element `count` times. `array_repeat(1, 3) -> [1, 1, 1]` |
| array_remove(array, element) | Removes the first element from the array equal to the given value. `array_remove([1, 2, 2, 3, 2, 1, 4], 2) -> [1, 2, 3, 2, 1, 4]` |
| array_remove_n(array, element, max) | Removes the first `max` elements from the array equal to the given value. `array_remove_n([1, 2, 2, 3, 2, 1, 4], 2, 2) -> [1, 3, 2, 1, 4]` |
| array_remove_all(array, element) | Removes all elements from the array equal to the given value. `array_remove_all([1, 2, 2, 3, 2, 1, 4], 2) -> [1, 3, 1, 4]` |
| array_remove(array, element) | Removes the first element from the array equal to the given value. `NULL` elements already in the array are preserved when removing a non-`NULL` value, and `array_remove(array, NULL)` returns `NULL`. `array_remove([1, 2, NULL, 2, 4], 2) -> [1, NULL, 2, 4]` |
| array_remove_n(array, element, max) | Removes the first `max` elements from the array equal to the given value. `NULL` elements already in the array are preserved when removing a non-`NULL` value, and `array_remove_n(array, NULL, max)` returns `NULL`. `array_remove_n([1, 2, NULL, 2, 4], 2, 2) -> [1, NULL, 4]` |
| array_remove_all(array, element) | Removes all elements from the array equal to the given value. `NULL` elements already in the array are preserved when removing a non-`NULL` value, and `array_remove_all(array, NULL)` returns `NULL`. `array_remove_all([1, 2, NULL, 2, 4], 2) -> [1, NULL, 4]` |
| array_replace(array, from, to) | Replaces the first occurrence of the specified element with another specified element. `array_replace([1, 2, 2, 3, 2, 1, 4], 2, 5) -> [1, 5, 2, 3, 2, 1, 4]` |
| array_replace_n(array, from, to, max) | Replaces the first `max` occurrences of the specified element with another specified element. `array_replace_n([1, 2, 2, 3, 2, 1, 4], 2, 5, 2) -> [1, 5, 5, 3, 2, 1, 4]` |
| array_replace_all(array, from, to) | Replaces all occurrences of the specified element with another specified element. `array_replace_all([1, 2, 2, 3, 2, 1, 4], 2, 5) -> [1, 5, 5, 3, 5, 1, 4]` |
Expand Down
29 changes: 25 additions & 4 deletions docs/source/user-guide/sql/scalar_functions.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3880,7 +3880,7 @@ _Alias of [array_prepend](#array_prepend)._

### `array_remove`

Removes the first element from the array equal to the given value.
Removes the first element from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.

```sql
array_remove(array, element)
Expand All @@ -3900,6 +3900,13 @@ array_remove(array, element)
+----------------------------------------------+
| [1, 2, 3, 2, 1, 4] |
+----------------------------------------------+

> select array_remove([1, 2, NULL, 2, 4], 2);
+---------------------------------------------------+
| array_remove(List([1,2,NULL,2,4]),Int64(2)) |
+---------------------------------------------------+
| [1, NULL, 2, 4] |
+---------------------------------------------------+
```

#### Aliases
Expand All @@ -3908,7 +3915,7 @@ array_remove(array, element)

### `array_remove_all`

Removes all elements from the array equal to the given value.
Removes all elements from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.

```sql
array_remove_all(array, element)
Expand All @@ -3928,6 +3935,13 @@ array_remove_all(array, element)
+--------------------------------------------------+
| [1, 3, 1, 4] |
+--------------------------------------------------+

> select array_remove_all([1, 2, NULL, 2, 4], 2);
+-----------------------------------------------------+
| array_remove_all(List([1,2,NULL,2,4]),Int64(2)) |
+-----------------------------------------------------+
| [1, NULL, 4] |
+-----------------------------------------------------+
```

#### Aliases
Expand All @@ -3936,10 +3950,10 @@ array_remove_all(array, element)

### `array_remove_n`

Removes the first `max` elements from the array equal to the given value.
Removes the first `max` elements from the array equal to the given value. NULL elements already in the array are preserved when removing a non-NULL value. If `element` evaluates to NULL, the result is NULL rather than removing NULL entries.

```sql
array_remove_n(array, element, max))
array_remove_n(array, element, max)
```

#### Arguments
Expand All @@ -3957,6 +3971,13 @@ array_remove_n(array, element, max))
+---------------------------------------------------------+
| [1, 3, 2, 1, 4] |
+---------------------------------------------------------+

> select array_remove_n([1, 2, NULL, 2, 4], 2, 2);
+----------------------------------------------------------+
| array_remove_n(List([1,2,NULL,2,4]),Int64(2),Int64(2)) |
+----------------------------------------------------------+
| [1, NULL, 4] |
+----------------------------------------------------------+
```

#### Aliases
Expand Down