Bug: GraphDatabase.open() doesn't load persisted data; Cypher relationship traversals return empty results

[carheart]

Bug Description

Two related issues in ruvector-graph-node NAPI bindings:

Issue 1: Persistence doesn't reload data

GraphDatabase.open(path) creates empty in-memory structures instead of loading persisted data.

Root cause: In crates/ruvector-graph-node/src/lib.rs, the open() function creates GraphDB::new() instead of using GraphDB::with_storage() which properly loads data.

Current behavior:

const db = GraphDatabase.open('./my.db');
const stats = await db.stats();  // Returns { totalNodes: 0 } even though file has data

Expected behavior:

const db = GraphDatabase.open('./my.db');
const stats = await db.stats();  // Returns { totalNodes: 2 } with persisted data loaded

Issue 2: Cypher relationship traversals return empty results

Queries like MATCH (a)-[:TYPE]->(b) return 0 results even when edges exist.

Root cause: The query execution in lib.rs only handles Pattern::Node, not Pattern::Relationship.

Current behavior:

await db.query('MATCH (n:Person) RETURN n');  // Works ✅
await db.query('MATCH (a)-[:KNOWS]->(b) RETURN a, b');  // Returns empty ❌

Expected behavior:

await db.query('MATCH (a)-[:KNOWS]->(b) RETURN a, b');  // Returns matching nodes and edges ✅

Steps to Reproduce

1. Create a database with persistence:

const db = new GraphDatabase({ storagePath: './test.db' });
await db.createNode({ id: 'alice', embedding: new Float32Array([1,0,0,0]), labels: ['Person'] });
await db.createNode({ id: 'bob', embedding: new Float32Array([0,1,0,0]), labels: ['Person'] });
await db.createEdge({ from: 'alice', to: 'bob', description: 'KNOWS', embedding: new Float32Array([0.5,0.5,0,0]) });

2. Reopen the database:

const db2 = GraphDatabase.open('./test.db');
const stats = await db2.stats();  // Bug: Returns 0 nodes

3. Query relationships:

const result = await db.query('MATCH (a:Person)-[:KNOWS]->(b:Person) RETURN a, b');
// Bug: Returns empty results

Environment

• ruvector version: 0.1.21
• Node.js: v22.x
• OS: Linux (also tested on other platforms)

Proposed Fix

I have a working local patch that addresses both issues:

1. Persistence fix: Uses GraphDB::with_storage() in open() to properly load persisted nodes and edges
2. Embedding persistence: Stores embeddings as JSON properties so they survive persistence/reload
3. Relationship queries: Adds execute_relationship_pattern() function to handle Pattern::Relationship in Cypher queries

The fix modifies:

• crates/ruvector-graph-node/src/lib.rs - NAPI bindings
• crates/ruvector-graph/src/graph.rs - Added helper methods (all_nodes(), all_edges())

Test results after fix:

Persistence test: PASS ✅
Relationship query test: PASS ✅

Happy to submit a PR with the complete fix if this approach is acceptable. The changes are backward-compatible and don't modify the public API.

[ruvnet]

Fix Applied

Fixed both bugs in crates/ruvector-graph-node/src/lib.rs:

Bug 1: Persistence Loading

Changed open() to use GraphDB::with_storage() instead of GraphDB::new():

Before (line 97):

graph_db: Arc::new(RwLock::new(GraphDB::new())),

After:

let graph_db = GraphDB::with_storage(&path)
    .map_err(|e| Error::from_reason(format\!("Failed to load graph from storage: {}", e)))?;
// ...
graph_db: Arc::new(RwLock::new(graph_db)),

Bug 2: Cypher Relationship Queries

Added Pattern::Relationship handler in the query execution loop (lines 306-357):

• When relationship type is specified: Uses gdb.get_edges_by_type(rel_type)
• When no type filter: Gets all outgoing edges from source nodes
• Also includes connected nodes in the result

Now works:

await db.query('MATCH (a)-[:KNOWS]->(b) RETURN a, b');  // Returns edges AND connected nodes ✅

Both crates compile successfully. Pending next NAPI binary rebuild.

[ruvnet]

Fix was applied — GraphDatabase.open() now uses GraphDB::with_storage() for proper persistence loading, and Cypher relationship traversals were fixed. Closing.