neo4j-modeling-skill

When to Use

• Designing graph model from scratch (domain → nodes, rels, props)
• Reviewing existing model for anti-patterns
• Deciding node vs property vs relationship vs label
• Migrating relational or document schema to graph
• Designing intermediate nodes for n-ary or complex relationships
• Detecting and mitigating supernode / high-fanout problems
• Choosing and creating constraints + indexes for a model

When NOT to Use

• Writing or optimizing Cypher → neo4j-cypher-skill
• Spring Data Neo4j (@Node, @Relationship) → neo4j-spring-data-skill
• GraphQL type definitions → neo4j-graphql-skill
• Importing data (LOAD CSV, APOC import) → neo4j-import-skill

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Inspect Before Designing

On existing database, run first — never propose changes without current state:

CALL db.schema.visualization() YIELD nodes, relationships RETURN nodes, relationships;
SHOW CONSTRAINTS YIELD name, type, labelsOrTypes, properties RETURN name, type, labelsOrTypes, properties;
SHOW INDEXES YIELD name, type, labelsOrTypes, state WHERE state = 'ONLINE' RETURN name, type, labelsOrTypes;

If APOC available:

CALL apoc.meta.schema() YIELD value RETURN value;

MCP tool map:

Operation	Tool
Inspect schema	get-schema
SHOW CONSTRAINTS, SHOW INDEXES	read-cypher
CREATE CONSTRAINT ... IF NOT EXISTS	write-cypher (show + confirm first)

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Defaults — Apply to Every Model

1. Use-case first — list 5+ queries the model must answer before designing
2. Nodes = entities (nouns) with identity; rels = connections (verbs) with direction
3. Labels PascalCase; rel types SCREAMING_SNAKE_CASE; properties camelCase
4. Every node type used in MERGE has a uniqueness constraint on its key property
5. Add property type constraints (REQUIRE n.prop IS :: STRING) where the type is known — helps the query planner and catches bad writes early
6. No generic labels (:Entity, :Node, :Thing); no generic rel types (:RELATED_TO, :HAS)
7. Security labels (used for row-level access control) should start with a common prefix (e.g. Sec) so application code can reliably filter them out of the domain schema
8. Rel direction encodes semantic meaning — not arbitrary
9. Inspect schema before proposing any change on an existing database
10. All constraint/index DDL uses IF NOT EXISTS — safe to rerun
11. On Neo4j 2026.02+ (Enterprise/Aura): consider ALTER CURRENT GRAPH TYPE SET { … } or EXTEND GRAPH TYPE WITH { … } to declare the full model in one block instead of individual CREATE CONSTRAINT statements — see neo4j-cypher-skill/references/graph-type.md. PREVIEW — syntax may change before GA.

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Key Patterns

Node vs Relationship vs Property — Decision Table

Question	Answer	Model as
Is it a thing with identity, queried as entry point?	Yes	Node
Is it a connection between two things with direction?	Yes	Relationship
Does the connection have its own properties or multiple targets?	Yes	Intermediate node
Is it a scalar always returned with its parent, never filtered alone?	Yes	Property on parent
Is it a category used for type-based filtering or path traversal?	Yes	Label (not a property)
Does the same attribute value repeat across many nodes (low cardinality)?	Yes	Label, not a property node
Is it a fact connecting >2 entities?	Yes	Intermediate node

Property vs Label — Decision Table

Use label when	Use property when
Values are few, fixed, used as traversal filters (WHERE n:Active)	Values are many, dynamic, or unique per node
You traverse by type (MATCH (n:VIPCustomer))	You filter by value (WHERE n.tier = 'vip')
Category drives index selection	Fine-grained value drives range scans
Example: :Active, :Verified, :Premium	Example: status, score, email

Rule: adding a label is cheap; scanning all :Label nodes is fast. Never model high-cardinality values as labels.

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Intermediate Node Pattern

Use when a relationship needs its own properties, connects >2 entities, or is independently queryable.

Before (relationship with property — limited):

(Person)-[:ACTED_IN {role: "Neo"}]->(Movie)
// Cannot query roles independent of movies

After (intermediate node — queryable, extensible):

(Person)-[:PLAYED]->(Role {name: "Neo"})-[:IN]->(Movie)
// MATCH (r:Role) WHERE r.name STARTS WITH 'Neo' RETURN r

Employment overlap example:

// Find colleagues who overlapped at same company
MATCH (p1:Person)-[:WORKED_AT]->(e1:Employment)-[:AT]->(c:Company)<-[:AT]-(e2:Employment)<-[:WORKED_AT]-(p2:Person)
WHERE p1 <> p2
  AND e1.startDate <= e2.endDate AND e2.startDate <= e1.endDate
RETURN p1.name, p2.name, c.name

Promote relationship to intermediate node when:

• Relationship has >2 properties
• Relationship is the subject of another query
• Multiple entities share the same connection context
• You need to connect >2 entities in one fact

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Relational → Graph Migration Table

Relational construct	Graph equivalent	Notes
Table row	Node	One label per table (add more as needed)
Column (scalar)	Node property
Primary key	Uniqueness constraint property	Use tmdbId, not id (too generic)
Foreign key	Relationship	Direction: from dependent → referenced
Many-to-many junction table	Intermediate node	Especially if junction has own columns
Junction table (no own columns)	Direct relationship	Simpler; upgrade to intermediate node later
NULL FK (optional relation)	Absent relationship	No node created; absence is the signal
Polymorphic FK (Rails-style)	Multiple labels or relationship types	Split into type-specific rels
Self-referential FK	Same-label relationship	:Employee {managerId} → (e)-[:REPORTS_TO]->(m)
Audit/history columns	Intermediate versioning node	See References for versioning pattern

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Supernode Detection and Mitigation

Detect:

// Find top-10 highest-degree nodes
MATCH (n)
RETURN labels(n) AS labels, elementId(n) AS id, count{ (n)--() } AS degree
ORDER BY degree DESC LIMIT 10

Node with degree >> median for its label = supernode candidate. Any node with >100K relationships will degrade traversal queries that pass through it.

Causes:

• Domain supernodes: airports, celebrities, popular hashtags — unavoidable
• Modeling supernodes: gender, country, status modeled as nodes with millions of edges — avoidable

Mitigation strategies (in priority order):

Strategy	When to use	Implementation
Query direction	Directional asymmetry exists	Query from low-degree side; exploit direction
Relationship type split	Supernode serves multiple roles	:FOLLOWS + :FAN instead of single :RELATED_TO
Label segregation	Supernode conflates entity types	:Celebrity vs :User → query only relevant subtype
Bucket pattern	Time-series or high-volume event nodes	See below
Avoid modeling	Low-cardinality categoricals	Use label instead of node (:Active not (:Status {name:"Active"}))
Join hint	Query tuning last resort	USING JOIN ON n in Cypher

Bucket pattern (time-series / high-volume):

// Instead of: (:User)-[:VIEWED]->(:Page) (millions of rels per user)
// Bucket by hour:
(u:User)-[:VIEWED_IN]->(b:ViewBucket {userId: u.id, hour: '2025-04-28T14'})-[:VIEWED]->(p:Page)

// Query last hour's views without traversing full history:
MATCH (u:User {id: $uid})-[:VIEWED_IN]->(b:ViewBucket {hour: $hour})-[:VIEWED]->(p)
RETURN p.url

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Naming Conventions

Element	Convention	Good	Bad
Node label	PascalCase, singular noun	:Person, :BlogPost	:person, :blog_posts, :Entity
Relationship type	SCREAMING_SNAKE_CASE, verb phrase	:ACTED_IN, :WORKS_FOR	:actedin, :relatedTo, :HAS
Property key	camelCase	firstName, createdAt	FirstName, first_name
Constraint name	snake_case descriptive	person_id_unique	constraint1
Index name	snake_case descriptive	person_name_idx	index2

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Schema Enforcement — What to Create for Each Element

Run all DDL with IF NOT EXISTS. Apply before importing data.

// 1. Uniqueness constraint — every node type used in MERGE
CREATE CONSTRAINT person_id_unique IF NOT EXISTS
  FOR (p:Person) REQUIRE p.id IS UNIQUE;

// 2. Existence constraint (Enterprise) — mandatory properties
CREATE CONSTRAINT person_name_exists IF NOT EXISTS
  FOR (p:Person) REQUIRE p.name IS NOT NULL;

// 3. Property type constraint (Enterprise) — enforce data type
CREATE CONSTRAINT person_born_integer IF NOT EXISTS
  FOR (p:Person) REQUIRE p.born IS :: INTEGER;

// 4. Key constraint (Enterprise) — unique + exists in one
CREATE CONSTRAINT movie_tmdbid_key IF NOT EXISTS
  FOR (m:Movie) REQUIRE m.tmdbId IS NODE KEY;

// 5. Range index — equality and range filters on properties
CREATE INDEX person_name_idx IF NOT EXISTS
  FOR (p:Person) ON (p.name);

// 6. Fulltext index — CONTAINS, STARTS WITH, free text search
CREATE FULLTEXT INDEX person_fulltext IF NOT EXISTS
  FOR (n:Person) ON EACH [n.name, n.bio];

// 7. Vector index — embedding similarity search
CREATE VECTOR INDEX chunk_embedding_idx IF NOT EXISTS
  FOR (c:Chunk) ON (c.embedding)
  OPTIONS { indexConfig: { `vector.dimensions`: 1536, `vector.similarity_function`: 'cosine' } };

// 8. Relationship index — filter on rel properties
CREATE INDEX acted_in_year_idx IF NOT EXISTS
  FOR ()-[r:ACTED_IN]-() ON (r.year);

After creating indexes, poll until ONLINE:

SHOW INDEXES YIELD name, state WHERE state <> 'ONLINE' RETURN name, state;

Do NOT use an index until state = ONLINE.

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Vector / Embedding Property Modeling

Store embeddings on dedicated :Chunk nodes, never on business nodes:

(:Document)-[:HAS_CHUNK]->(c:Chunk {text: "...", embedding: [...]})

Rules:

• Chunk node: text (source text), embedding (float array), chunkIndex (int)
• Parent document: metadata only (title, url, createdAt)
• Vector index on c.embedding only
• Chunk size 200–500 tokens with 20% overlap is production default [field]
• Do NOT put embedding on :Document — makes the node too large and pollutes traversal

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Anti-Patterns Table

Anti-pattern	Problem	Fix
Generic labels :Entity, :Node	No filtering benefit; all nodes scan	Use domain labels :Person, :Product
Generic rel types :RELATED_TO, :HAS	Can't filter by relationship type	Use semantic types :PURCHASED, :AUTHORED
Low-cardinality value as node	Supernode (:Status {name:"active"} → millions of edges)	Use label :Active instead
Property as label (n.type = 'VIP' + :VIP label both exist)	Inconsistency, duplication	Pick one; prefer label if used in traversal
Storing embeddings on business node	Node bloat, slow traversal	Dedicated :Chunk node
MERGE without uniqueness constraint	Duplicate nodes silently created	Add constraint before any MERGE
Missing relationship direction meaning	Arbitrary direction; confusing model	Direction = semantic flow of action
Junction table modeled as bare property	Loses history and extensibility	Intermediate node with its own properties
id as property name	id(n) is a deprecated Cypher function (use elementId(n)); bare id is fine as a property name in practice, but domain-qualified names (personId, movieId) are clearer and avoid any future ambiguity	Prefer personId, movieId, tmdbId where it aids readability
All dates as strings	No range queries; no temporal operators	Use Neo4j date() or datetime() type

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Output Format — Schema Assessment

When reviewing an existing model:

## Schema Assessment

### Compliant
- [constraint / pattern that is correct]

### Issues Found
#### [Title] — Severity: ERROR / WARNING / INFO
- **Current**: what the model does
- **Problem**: why it is an issue
- **Fix**: specific Cypher DDL or model change

## Recommended Schema
### Node Labels
- :Label {key: TYPE, prop: TYPE, ...}  → constraints: [list]

### Relationships
- (:LabelA)-[:TYPE {prop: TYPE}]->(:LabelB)

### Constraints to Create
[CREATE CONSTRAINT ... statements]

### Indexes to Create
[CREATE INDEX ... statements]

Severity semantics:

Severity	Meaning	Action
ERROR	Model correctness failure (duplicates possible, data loss risk)	Stop; fix before proceeding
WARNING	Performance or extensibility risk	Report; ask user before proceeding
INFO	Style or convention deviation	Surface; continue

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Provenance Labels

• [official] — stated directly in Neo4j docs
• [derived] — follows from documented behavior
• [field] — community heuristic; treat as default but validate

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Checklist

• Use cases (≥5 queries) defined before modeling
• Schema inspected on existing database before changes proposed
• Every MERGE-target node label has a uniqueness constraint
• No generic labels (:Entity, :Node, :Thing)
• No generic relationship types (:RELATED_TO, :HAS, :CONNECTED_TO)
• Relationship direction encodes semantic meaning
• N-ary or propertied relationships use intermediate nodes
• High-cardinality values stored as properties, not nodes
• Low-cardinality categoricals used as labels, not property nodes
• Embeddings on dedicated :Chunk nodes, not business nodes
• Supernode candidates identified and mitigated
• All DDL uses IF NOT EXISTS
• Indexes polled to ONLINE before use
• Assessment output follows the structured format above
• Every prohibition paired with a concrete fix

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References

Load on demand:

• references/modeling-patterns.md — time-series, versioning, multi-tenancy, linked list, access control patterns
• Neo4j Data Modeling Guide
• Neo4j Modeling Tips
• GraphAcademy: Graph Data Modeling Fundamentals
• Super Nodes — All About Super Nodes (David Allen)