Struct CompositeRow 

pub struct CompositeRow { /* private fields */ }

A composite row that references values from two source rows.

This is the key optimization for joins - instead of cloning all values from both the left and right rows into a new row, we keep references to both and provide a unified view.

Memory Layout

CompositeRow
├── left: Row (owned)
├── right: Row (owned)
└── left_cols: usize

Logical columns: [left_col_0, left_col_1, ..., right_col_0, right_col_1, ...]
                 |<--- left_cols --->|<--- right cols --->|

Implementations

impl CompositeRow

pub fn new(left: Row, right: Row) -> Self

Create a new composite row from left and right parts.

pub fn with_counts(left: Row, right: Row, left_cols: usize) -> Self

Create a composite row with explicit column count.

Use this when the left row has been modified (e.g., projection).

pub fn len(&self) -> usize

Get the total number of columns.

pub fn is_empty(&self) -> bool

Check if this composite row is empty.

pub fn get(&self, idx: usize) -> Option<&Value>

Get a value by index without cloning.

Indexes 0..left_cols return from the left row. Indexes left_cols..total return from the right row.

pub fn left(&self) -> &Row

Get a reference to the left row.

pub fn right(&self) -> &Row

Get a reference to the right row.

pub fn materialize(&self) -> Row

Materialize into an owned Row (cloning version).

This creates a single Row by copying all values from both sides. Only call this when the final result needs to be stored. Prefer materialize_owned() when you can consume the CompositeRow.

pub fn materialize_owned(self) -> Row

Materialize into an owned Row by moving values (zero-copy).

This consumes the CompositeRow and moves all values without cloning. Use this instead of materialize() when you no longer need the CompositeRow.

pub fn into_parts(self) -> (Row, Row)

Decompose into the left and right rows.

Trait Implementations

impl Clone for CompositeRow

fn clone(&self) -> CompositeRow

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CompositeRow

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for CompositeRow

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.