Struct ColumnNullable 

pub struct ColumnNullable { /* private fields */ }

Column for nullable values

Stores a nested column and a ColumnUInt8 for null flags (1 = null, 0 = not null).

Wire Format:

[null_bitmap: UInt8 * num_rows][nested_column_data]

ClickHouse Reference:

• Documentation: https://clickhouse.com/docs/en/sql-reference/data-types/nullable
• Best Practices: https://clickhouse.com/docs/en/cloud/bestpractices/avoid-nullable-columns

Implementations

impl ColumnNullable

pub fn new(type_: Type) -> Self

Create a new nullable column from a nullable type

pub fn with_nested(nested: ColumnRef) -> Self

Create a new nullable column wrapping an existing nested column

pub fn from_parts(nested: ColumnRef, nulls: ColumnRef) -> Result<Self>

Create with both nested and nulls columns

pub fn with_capacity(type_: Type, capacity: usize) -> Self

Create with reserved capacity

pub fn append(&mut self, isnull: bool)

Append a null flag (matches C++ API)

pub fn append_null(&mut self)

Append a null value

pub fn append_non_null(&mut self)

Append a non-null value (the nested column should be updated separately)

pub fn is_null(&self, index: usize) -> bool

Check if value at index is null (matches C++ IsNull)

pub fn nested<T: Column + 'static>(&self) -> &T

Get a reference to the nested column as a specific type

Example

let col: ColumnNullable = /* ... */;
let nested: &ColumnUInt32 = col.nested();

pub fn nested_mut<T: Column + 'static>(&mut self) -> &mut T

Get mutable reference to the nested column as a specific type

Example

let mut col: ColumnNullable = /* ... */;
let nested_mut: &mut ColumnUInt32 = col.nested_mut();

pub fn nested_ref(&self) -> ColumnRef

Get the nested column as a ColumnRef (Arc<dyn Column>)

pub fn nested_ref_mut(&mut self) -> &mut ColumnRef

Get mutable access to the nested ColumnRef for dynamic dispatch scenarios

This is useful when you need to modify the nested column but don’t know its concrete type at compile time.

pub fn nulls(&self) -> ColumnRef

Get the nulls column (matches C++ Nulls)

pub fn append_nullable(&mut self, value: Option<u32>)

Append a nullable UInt32 value (convenience method for tests)

pub fn is_null_at(&self, index: usize) -> bool

Check if value at index is null (alias for is_null)

pub fn at(&self, _index: usize) -> ColumnRef

Get a reference to the value at the given index Returns the nested column for accessing the value (check is_null first!)

pub fn len(&self) -> usize

Get the number of elements (alias for size())

pub fn is_empty(&self) -> bool

Check if the nullable column is empty

Trait Implementations

impl Clone for ColumnNullable

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Column for ColumnNullable

fn column_type(&self) -> &Type

Get the type of this column

fn size(&self) -> usize

Get the number of rows in this column

fn clear(&mut self)

Clear all data from the column

fn reserve(&mut self, new_cap: usize)

Reserve capacity for at least new_cap elements

fn append_column(&mut self, other: ColumnRef) -> Result<()>

Append another column’s data to this column

fn load_from_buffer(&mut self, buffer: &mut &[u8], rows: usize) -> Result<()>

Load column data from byte buffer

fn save_prefix(&self, buffer: &mut BytesMut) -> Result<()>

Save column prefix to byte buffer (for types that need prefix data) Default implementation is a no-op. Override for types like LowCardinality, Array with special nested types. This matches C++ clickhouse-cpp’s SavePrefix pattern.

fn save_to_buffer(&self, buffer: &mut BytesMut) -> Result<()>

Save column data to byte buffer

fn clone_empty(&self) -> ColumnRef

Create an empty clone of this column (same type, no data)

fn slice(&self, begin: usize, len: usize) -> Result<ColumnRef>

Create a slice of this column

fn as_any(&self) -> &dyn Any

Downcast to a concrete column type

fn as_any_mut(&mut self) -> &mut dyn Any

Downcast to a mutable concrete column type

fn load_prefix(&mut self, _buffer: &mut &[u8], _rows: usize) -> Result<()>

Load column prefix from byte buffer (for types that need prefix data) Default implementation is a no-op. Override for types like LowCardinality. This matches C++ clickhouse-cpp’s LoadPrefix pattern.