Gremlin Query Language¶

Gremlin is a graph traversal language developed by Apache TinkerPop. Grafeo supports Gremlin as an optional query language via feature flag.

Overview¶

Gremlin uses a functional, step-based approach to traverse and manipulate graph data. It's designed around the concept of traversing vertices and edges through a series of chained steps.

Enabling Gremlin¶

Gremlin support is optional and requires a feature flag:

cargo add grafeo-engine --features gremlin

uv add grafeo[gremlin]

Quick Reference¶

Basic Examples¶

Finding Vertices¶

// All vertices
g.V()

// Vertices with a specific label
g.V().hasLabel('Person')

// Vertex with specific property
g.V().has('name', 'Alice')

// Multiple conditions
g.V().hasLabel('Person').has('age', gt(25))

Traversing Edges¶

// Friends of Alice
g.V().has('name', 'Alice').out('KNOWS')

// People who know Bob
g.V().has('name', 'Bob').in('KNOWS')

// Two-hop traversal
g.V().has('name', 'Alice').out('KNOWS').out('KNOWS')

Getting Properties¶

// Get names of all people
g.V().hasLabel('Person').values('name')

// Get multiple properties
g.V().hasLabel('Person').valueMap('name', 'age')

Aggregations¶

// Count all people
g.V().hasLabel('Person').count()

// Count friends
g.V().has('name', 'Alice').out('KNOWS').count()

Python Usage¶

import grafeo

db = grafeo.GrafeoDB()

# Create some data
db.execute("INSERT (:Person {name: 'Alice', age: 30})")
db.execute("INSERT (:Person {name: 'Bob', age: 25})")
db.execute("""
    MATCH (a:Person {name: 'Alice'}), (b:Person {name: 'Bob'})
    INSERT (a)-[:KNOWS {since: 2020}]->(b)
""")

# Query with Gremlin
result = db.execute_gremlin("g.V().hasLabel('Person').values('name')")
for row in result:
    print(row)

# Traverse relationships
friends = db.execute_gremlin("g.V().has('name', 'Alice').out('KNOWS').values('name')")

Rust Usage¶

use grafeo_engine::GrafeoDB;

let db = GrafeoDB::new_in_memory();

// Create data with GQL
db.execute("INSERT (:Person {name: 'Alice'})").unwrap();

// Query with Gremlin
let result = db.execute_gremlin("g.V().hasLabel('Person')").unwrap();

Supported Steps¶

Source Steps¶

• g.V() - Start traversal from vertices
• g.V(id) - Start from specific vertex

Filter Steps¶

• hasLabel(label) - Filter by vertex label
• has(key, value) - Filter by property equality
• has(key, predicate) - Filter by property predicate

Traversal Steps¶

• out(label?) - Traverse outgoing edges
• in(label?) - Traverse incoming edges
• both(label?) - Traverse both directions
• outE(label?) - Get outgoing edges
• inE(label?) - Get incoming edges

Property Steps¶

• values(key) - Get property values
• valueMap(keys...) - Get multiple properties as map

Terminal Steps¶

• count() - Count elements
• limit(n) - Limit results

Learn More¶