neo4j-modeling-skill

Imported from cardox6/steuer-graph (.agents/skills/neo4j-modeling-skill/SKILL.md). Install upstream with npx skills add cardox6/steuer-graph --skill neo4j-modeling-skill. Copyright stays with the author.

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

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:

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 2026.06+ (Enterprise/Aura, GA): declare the full model in one block with ALTER CURRENT GRAPH TYPE SET { … }, extend it with ALTER CURRENT GRAPH TYPE ADD { … }, instead of individual CREATE CONSTRAINT statements — see neo4j-cypher-skill/references/graph-type.md. On 2026.02–2026.05 the same syntax is preview.

Key Patterns

Node vs Relationship vs Property — Decision Table

Property vs Label — Decision Table

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

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

Relational → Graph Migration Table

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):

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

Naming Conventions

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.

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

Anti-Patterns Table

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:

Provenance Labels

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

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

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)