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Neo4j Schema

Cronus uses Neo4j as its graph database. The schema is designed to be extensible - genealogy is the first use case, but the same patterns support org charts, professional networks, and other relationship graphs.

Node Types​

Person​

Primary entity representing an individual.

(:Person {
  id: String,           // UUID, primary key
  given_name: String,
  surname: String,
  birth_date: Date,
  birth_place: String,
  death_date: Date,
  death_place: String,
  gender: String,       // 'M', 'F', 'U' (unknown)
  notes: String,
  created_at: DateTime,
  updated_at: DateTime,
  source: String        // 'manual', 'gedcom', 'familysearch'
})

Event​

Life events (births, deaths, marriages, etc.)

(:Event {
  id: String,
  event_type: String,   // 'birth', 'death', 'marriage', 'divorce', etc.
  date: Date,
  place: String,
  notes: String
})

Place​

Locations with optional hierarchy.

(:Place {
  id: String,
  name: String,
  full_name: String,    // "Salt Lake City, Utah, USA"
  latitude: Float,
  longitude: Float
})

Source​

Citations and documentation.

(:Source {
  id: String,
  title: String,
  author: String,
  publication: String,
  url: String,
  notes: String
})

Relationship Types​

Family Relationships​

// Parent-child (directional)
(parent:Person)-[:PARENT_OF {
  relationship_type: String  // 'biological', 'adoptive', 'step', 'foster'
}]->(child:Person)

// Inverse for efficient queries
(child:Person)-[:CHILD_OF {
  relationship_type: String
}]->(parent:Person)

// Spousal relationship
(person1:Person)-[:SPOUSE_OF {
  marriage_date: Date,
  marriage_place: String,
  divorce_date: Date,
  relationship_type: String  // 'married', 'domestic_partner', 'engaged'
}]->(person2:Person)

Event Relationships​

// Person participated in event
(person:Person)-[:PARTICIPATED_IN {
  role: String  // 'subject', 'witness', 'officiant'
}]->(event:Event)

// Event occurred at place
(event:Event)-[:OCCURRED_AT]->(place:Place)

Source Relationships​

// Any node can be cited
(node)-[:CITED_BY {
  citation_text: String,
  page: String
}]->(source:Source)

Indexes​

// Primary lookups
CREATE INDEX person_id FOR (p:Person) ON (p.id);
CREATE INDEX event_id FOR (e:Event) ON (e.id);
CREATE INDEX place_id FOR (pl:Place) ON (pl.id);
CREATE INDEX source_id FOR (s:Source) ON (s.id);

// Search indexes
CREATE INDEX person_surname FOR (p:Person) ON (p.surname);
CREATE INDEX person_given FOR (p:Person) ON (p.given_name);

// Full-text search
CREATE FULLTEXT INDEX person_name_search FOR (p:Person) ON EACH [p.given_name, p.surname];

Core Graph Queries​

These queries work on ANY schema with parent/child relationships.

Ancestors​

MATCH (p:Person {id: $person_id})-[:CHILD_OF*]->(ancestor:Person)
RETURN ancestor

Descendants​

MATCH (p:Person {id: $person_id})-[:PARENT_OF*]->(descendant:Person)
RETURN descendant

Common Ancestors​

MATCH (p1:Person {id: $person1_id})-[:CHILD_OF*]->(ancestor:Person)<-[:CHILD_OF*]-(p2:Person {id: $person2_id})
RETURN DISTINCT ancestor

Relationship Path​

MATCH path = shortestPath(
  (p1:Person {id: $person1_id})-[:PARENT_OF|CHILD_OF|SPOUSE_OF*]-(p2:Person {id: $person2_id})
)
RETURN path