Struct LabelIndex 

pub struct LabelIndex { /* private fields */ }

Index mapping label names to the set of node IDs carrying that label.

Each label maps to a RoaringBitmap of node IDs (u32). When a MATCH query specifies (n:Person), the index returns the bitmap of all Person-labeled nodes in O(1), avoiding a full payload scan.

Limitations

RoaringBitmap only supports u32 IDs. Node IDs exceeding u32::MAX are silently skipped (logged at warn level on insert).

Example

let mut index = LabelIndex::new();
index.insert("Person", 1);
index.insert("Person", 2);
index.insert("Company", 3);

let persons = index.lookup("Person");
assert!(persons.map_or(false, |b| b.contains(1)));
assert!(persons.map_or(false, |b| b.contains(2)));

Implementations

impl LabelIndex

pub fn new() -> Self

Creates a new empty label index.

pub fn index_from_payload(&mut self, node_id: u64, payload: &Value) -> usize

Indexes a node under one or more labels.

Extracts _labels from the JSON payload (expected to be an array of strings) and inserts the node ID into the bitmap for each label.

Returns the number of labels successfully indexed (0 if payload has no _labels array or node ID exceeds u32::MAX).

pub fn insert(&mut self, label: &str, node_id: u64) -> bool

Inserts a single (label, node_id) pair into the index.

Returns true if the node was added (new entry). Returns false if the node ID exceeds u32::MAX or was already present.

pub fn remove_from_payload(&mut self, node_id: u64, payload: &Value)

Removes a node from all label bitmaps.

Call this before removing a node to keep the index consistent.

pub fn has_large_ids(&self) -> bool

Returns true if any node with _labels had an ID exceeding u32::MAX and could not be indexed. Callers should fall back to a full scan when this is true and the bitmap lookup returns empty results.

pub fn lookup(&self, label: &str) -> Option<&RoaringBitmap>

Returns the bitmap of node IDs carrying the given label.

Returns None if no nodes have been indexed with this label.

pub fn lookup_intersection(&self, labels: &[String]) -> Option<RoaringBitmap>

Returns the intersection of bitmaps for all required labels.

When a MATCH pattern requires multiple labels (e.g., (n:Person:Employee)), only nodes carrying ALL labels should match. Returns None if any required label has no indexed nodes (empty intersection).

pub fn label_count(&self) -> usize

Returns the number of distinct labels in the index.

pub fn is_empty(&self) -> bool

Returns true if the index contains no entries.

pub fn clear(&mut self)

Clears all entries from the index.

pub fn memory_usage(&self) -> usize

Returns an estimated memory usage in bytes.

Trait Implementations

impl Debug for LabelIndex

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

Formats the value using the given formatter.

impl Default for LabelIndex

fn default() -> LabelIndex

Returns the “default value” for a type.