Struct ScanByLabel 

pub struct ScanByLabel { /* private fields */ }

Yields chunks of node slot numbers for a single label.

Each output chunk contains one COL_ID_SLOT column with at most CHUNK_CAPACITY consecutive slot numbers.

Phase 2: uses a cursor-based approach (next_slot/end_slot) rather than pre-allocating the entire Vec<u64> at construction time. This reduces startup allocation from O(hwm) to O(1) — critical for large labels.

Implementations

impl ScanByLabel

pub fn new(hwm: u64) -> Self

Create a ScanByLabel operator.

hwm — high-water mark from NodeStore::hwm_for_label(label_id). Emits slot numbers 0..hwm in order, allocating at most one chunk at a time.

pub fn from_slots(slots: Vec<u64>) -> Self

Create from a pre-built slot list (for tests and custom scan patterns).

Retained for backward compatibility with existing unit tests and special scan patterns. Prefer ScanByLabel::new for production use.

Trait Implementations

impl PipelineOperator for ScanByLabel

fn next_chunk(&mut self) -> Result<Option<DataChunk>>

Pull the next chunk of output. Returns None when exhausted.

fn cardinality_hint(&self) -> Option<usize>

Estimated output cardinality (rows) hint for pre-allocation.