ffsshhttiikk Neo4j
What I do
I am a native graph database designed for connected data. I represent and store data as nodes (entities) and relationships (connections) with properties on both. I excel at traversing complex relationships, social network analysis, recommendation engines, fraud detection, and knowledge graphs. My query language, Cypher, provides an intuitive pattern-matching syntax for expressing graph traversals and queries.
When to use me
- Social networks and relationship-heavy applications
- Recommendation engines based on connections
- Fraud detection and anomaly identification
- Knowledge graphs and semantic web applications
- Network and IT infrastructure management
- Genealogy and organizational hierarchy queries
- Path finding and routing optimizations
- Master data management with complex relationships
- Supply chain and dependency analysis
Core Concepts
- Nodes and Labels: Entities with optional labels for categorizing (User, Product, Order)
- Relationships: Directed connections between nodes with types (FOLLOWS, PURCHASED, LOCATED_AT)
- Properties: Key-value attributes on both nodes and relationships
- Cypher Query Language: Declarative pattern-matching query language with ASCII-art syntax
- Graph Traversal: Efficient traversal of arbitrary-length relationship paths
- Indexes: Single-property and composite indexes on node properties for fast lookups
- Constraints: Uniqueness constraints, existence constraints, and node key constraints
- APOC Procedures: Extended library of procedures for advanced graph operations
- Graph Data Science: Built-in algorithms for centrality, community detection, and path finding
- Neo4j Bloom: Visual exploration tool for graph data discovery
Code Examples
Basic Connection and CRUD Operations
from neo4j import GraphDatabase
from neo4j.exceptions import ConstraintError
driver = GraphDatabase.driver(
"bolt://localhost:7687",
auth=("neo4j", "password"),
max_connection_lifetime=3600
)
def create_user(name, email, **kwargs):
with driver.session() as session:
result = session.run("""
CREATE (u:User {name: $name, email: $email, created_at: datetime()})
SET u += $kwargs
RETURN u
""", name=name, email=email, kwargs=kwargs)
return result.single()
def get_user_by_email(email):
with driver.session() as session:
result = session.run("""
MATCH (u:User {email: $email})
RETURN u
""", email=email)
return result.single()
def get_user_with_friends(user_email):
with driver.session() as session:
result = session.run("""
MATCH (user:User {email: $email})-[:FRIEND*1..2]-(friend:User)
WHERE user.email <> friend.email
WITH DISTINCT friend
OPTIONAL MATCH (friend)-[:PURCHASED]->(product:Product)
RETURN friend, collect(product) as products
""", email=email)
return [dict(record) for record in result]
def update_user_properties(email, **updates):
with driver.session() as session:
result = session.run("""
MATCH (u:User {email: $email})
SET u += $updates
RETURN u
""", email=email, updates=updates)
return result.single()
def delete_user(email):
with driver.session() as session:
result = session.run("""
MATCH (u:User {email: $email})
DETACH DELETE u
RETURN count(*) as deleted
""", email=email)
return result.single()["deleted"] > 0
Relationship Creation and Queries
def create_friendship(user1_email, user2_email):
with driver.session() as session:
result = session.run("""
MATCH (a:User {email: $email1}), (b:User {email: $email2})
WHERE a <> b
MERGE (a)-[:FRIEND {since: datetime()}]-(b)
RETURN a, b
""", email1=user1_email, email2=user2_email)
return result.single()
def get_mutual_friends(user1_email, user2_email):
with driver.session() as session:
result = session.run("""
MATCH (a:User {email: $email1})-[:FRIEND]-(mutual)-[:FRIEND]-(b:User {email: $email2})
WHERE a <> b
RETURN collect(mutual) as mutual_friends, count(mutual) as count
""", email1=user1_email, email2=user2_email)
return result.single()
def get_friends_of_friends(user_email, limit=50):
with driver.session() as session:
result = session.run("""
MATCH (user:User {email: $email})-[:FRIEND]->()-[:FRIEND]-(friend:User)
WHERE user <> friend AND NOT (user)-[:FRIEND]-(friend)
WITH friend, count(*) as common_friends
ORDER BY common_friends DESC
LIMIT $limit
RETURN friend, common_friends
""", email=user_email, limit=limit)
return [(dict(record["friend"]), record["common_friends"]) for record in result]
def record_purchase(user_email, product_sku, quantity=1):
with driver.session() as session:
result = session.run("""
MATCH (user:User {email: $email}), (product:Product {SKU: $sku})
MERGE (user)-[:PURCHASED {quantity: $quantity, at: datetime()}]->(product)
RETURN user, product
""", email=user_email, sku=product_sku, quantity=quantity)
return result.single()
def get_user_purchase_history(user_email, limit=50):
with driver.session() as session:
result = session.run("""
MATCH (user:User {email: $email})-[:PURCHASED]->(product:Product)
WITH product, purchase
ORDER BY purchase.at DESC
LIMIT $limit
RETURN product, purchase
""", email=user_email, limit=limit)
return [dict(record) for record in result]
Path Finding and Graph Algorithms
def find_shortest_path(start_email, end_email):
with driver.session() as session:
result = session.run("""
MATCH (start:User {email: $start}), (end:User {email: $end})
MATCH path = shortestPath((start)-[:FRIEND*..15]-(end))
RETURN nodes(path) as users, length(path) as distance
""", start=start_email, end=end_email)
return result.single()
def find_all_shortest_paths(start_email, end_email):
with driver.session() as session:
result = session.run("""
MATCH (start:User {email: $start}), (end:User {email: $end})
MATCH paths = allShortestPaths((start)-[:FRIEND*..10]-(end))
RETURN paths, length(paths) as hops
""", start=start_email, end=end_email)
return [dict(record) for record in result]
def get_influencers(limit=10):
with driver.session() as session:
result = session.run("""
MATCH (user:User)
WITH user, size((user)<-[:FRIEND]-()) as follower_count
ORDER BY follower_count DESC
LIMIT $limit
RETURN user.name, follower_count
""", limit=limit)
return [dict(record) for record in result]
def find_communities():
with driver.session() as session:
result = session.run("""
CALL gds.louvain.stream('user-graph', {relationshipTypes: ['FRIEND']})
YIELD nodeId, communityId
MATCH (u:User) WHERE id(u) = nodeId
RETURN communityId, collect(u.name) as members, count(*) as size
ORDER BY size DESC
""")
return [dict(record) for record in result]
def find_central_users():
with driver.session() as session:
result = session.run("""
CALL gds.betweenness.stream('user-graph', {relationshipTypes: ['FRIEND']})
YIELD nodeId, score
MATCH (u:User) WHERE id(u) = nodeId
RETURN u.name, score
ORDER BY score DESC
LIMIT 20
""")
return [dict(record) for record in result]
Recommendation Engine
def recommend_products_to_user(user_email, limit=10):
with driver.session() as session:
result = session.run("""
MATCH (user:User {email: $email})-[:PURCHASED]->(p1:Product)-[:PURCHASED]-()-[:PURCHASED]->(recommendation:Product)
WHERE NOT (user)-[:PURCHASED]->(recommendation) AND p1 <> recommendation
WITH recommendation, count(*) as score
ORDER BY score DESC
LIMIT $limit
RETURN recommendation, score
""", email=user_email, limit=limit)
return [(dict(record["recommendation"]), record["score"]) for record in result]
def recommend_friends(user_email, limit=10):
with driver.session() as session:
result = session.run("""
MATCH (user:User {email: $email})-[:FRIEND]->(friend:User)-[:FRIEND]->(suggestion:User)
WHERE user <> suggestion AND NOT (user)-[:FRIEND]-(suggestion)
WITH suggestion, count(*) as common_friends
ORDER BY common_friends DESC
LIMIT $limit
RETURN suggestion, common_friends
""", email=user_email, limit=limit)
return [(dict(record["suggestion"]), record["common_friends"]) for record in result]
def get_trending_products(timeframe="30d"):
with driver.session() as session:
result = session.run("""
MATCH (product:Product)<-[:PURCHASED]-(order:Order)
WHERE order.purchased_at >= datetime() - duration({days: 30})
WITH product, count(*) as purchase_count
ORDER BY purchase_count DESC
RETURN product.name, purchase_count
LIMIT 20
""")
return [dict(record) for record in result]
def find_similar_users(user_email, limit=10):
with driver.session() as session:
result = session.run("""
MATCH (user:User {email: $email})-[:PURCHASED]->(:Product)<-[:PURCHASED]-(similar:User)
WHERE user <> similar
WITH similar, count(*) as shared_purchases
ORDER BY shared_purchases DESC
LIMIT $limit
RETURN similar.name, similar.email, shared_purchases
""", email=user_email, limit=limit)
return [dict(record) for record in result]
Advanced Graph Operations
def create_company_hierarchy():
with driver.session() as session:
result = session.run("""
MATCH (ceo:Employee {title: 'CEO'})
OPTIONAL MATCH (ceo)-[:MANAGES*]->(report:Employee)
WITH ceo, collect(report) as all_reports
RETURN ceo.name as ceo, size(all_reports) as total_reports
""")
return result.single()
def find_employees_by_department(department_name):
with driver.session() as session:
result = session.run("""
MATCH (dept:Department {name: $dept})-[:HAS_MEMBER]->(emp:Employee)
RETURN emp.name, emp.title, emp.email
""", dept=department_name)
return [dict(record) for record in result]
def analyze_supply_chain():
with driver.session() as session:
result = session.run("""
MATCH path = (supplier:Supplier)-[:SUPPLIES*]->(manufacturer:Manufacturer)-[:PRODUCES]->(product:Product)
WITH supplier, product, length(path) as chain_length
RETURN supplier.name, collect(product.name) as products, chain_length
ORDER BY chain_length DESC
""")
return [dict(record) for record in result]
def detect_fraud_patterns():
with driver.session() as session:
result = session.run("""
MATCH (user:User)-[:PURCHASED]->(order:Order)
WITH user, count(order) as order_count, sum(order.total) as total_spent
WHERE order_count > 10 AND total_spent < 100
RETURN user.name, user.email, order_count, total_spent
LIMIT 50
""")
return [dict(record) for record in result]
def find_connected_components():
with driver.session() as session:
result = session.run("""
CALL gds.wcc.stream('social-graph', {relationshipTypes: ['FRIEND']})
YIELD nodeId, componentId
MATCH (u:User) WHERE id(u) = nodeId
RETURN componentId, collect(u.name) as members
""")
return [dict(record) for record in result]
Best Practices
- Use Constraints for Data Integrity: Create uniqueness constraints on frequently queried properties
- Index Wisely: Create indexes on properties used in WHERE clauses and MATCH patterns
- Avoid Cartesian Products: Be careful with unbounded pattern matching that can explode result sets
- Use Parameters in Queries: Always parameterize Cypher queries for performance and security
- Profile Your Queries: Use EXPLAIN and PROFILE to understand query execution plans
- Limit Path Lengths: Set maximum depth in path patterns to prevent infinite traversals
- Use MERGE Carefully: MERGE can create unintended patterns; use CREATE when you know node doesn't exist
- Leverage APOC Procedures: Use APOC for advanced operations like bulk imports and graph transformations
- Consider Graph Data Science: Use built-in algorithms for centrality, community detection, and embeddings
- Monitor Query Performance: Track slow queries and optimize patterns that cause full scans