Neo4j Cheatsheet

At a glance

Connect

Irodori accepts either a raw url or structured fields. Defaults match the adapter: host 127.0.0.1, port 7687, user neo4j, database neo4j, empty password.

Minimal raw form: bolt://neo4j:password@127.0.0.1:7687 (database selected separately, defaults to neo4j).

Query model

• You type Cypher; Irodori runs it through Graph::execute.
• Results become a table: columns = the ordered union of RETURN keys across records; each record fills known columns, missing keys → null.
• Node / relationship / path values render as JSON cells (their properties).
• Rows are capped at max_rows (default 10,000); the result is flagged truncated: true when more remain. Add an explicit LIMIT for large graphs.
• Version: Irodori reads it via CALL dbms.components().

Essential statements

-- Read a pattern
MATCH (p:Person)-[:ACTED_IN]->(m:Movie)
WHERE m.released >= 2000
RETURN p.name AS actor, m.title AS movie
ORDER BY m.released DESC
LIMIT 25;

-- Parameters (preferred over string interpolation)
MATCH (p:Person {name: $name}) RETURN p;

-- Create / upsert
CREATE (p:Person {name: 'Ada', born: 1815});
MERGE (p:Person {name: 'Ada'})            -- match-or-create on the key
  ON CREATE SET p.born = 1815
  ON MATCH  SET p.seen = timestamp();

-- Relate
MATCH (a:Person {name:'Ada'}), (m:Movie {title:'Analytics'})
MERGE (a)-[r:ACTED_IN {role:'self'}]->(m);

-- Aggregate / collect
MATCH (p:Person)-[:ACTED_IN]->(m)
RETURN p.name, count(m) AS films, collect(m.title) AS titles
ORDER BY films DESC;

-- Pipe with WITH, expand lists with UNWIND
UNWIND [1,2,3] AS n RETURN n*n AS square;

-- Variable-length path
MATCH path = (a:Person {name:'Ada'})-[:KNOWS*1..3]-(b:Person)
RETURN b.name, length(path) AS hops;

-- Delete safely (detach removes attached relationships)
MATCH (p:Person {name:'Ada'}) DETACH DELETE p;

Clause order to memorize: MATCH → WHERE → WITH → RETURN → ORDER BY → SKIP → LIMIT. WITH is the pipe between query parts (it also gates WHERE after aggregation).

Introspection

This is exactly what Irodori’s object browser runs against Neo4j:

CALL db.labels()              YIELD label              RETURN label;            -- node labels
CALL db.relationshipTypes()   YIELD relationshipType   RETURN relationshipType; -- rel types
CALL db.propertyKeys()        YIELD propertyKey        RETURN propertyKey;      -- property keys
SHOW INDEXES;                 -- indexes (4.x+)
SHOW CONSTRAINTS;             -- constraints (4.x+)
CALL dbms.components();       -- server name / version / edition

Indexes & constraints you will create often:

CREATE INDEX person_name IF NOT EXISTS FOR (p:Person) ON (p.name);
CREATE CONSTRAINT person_name_unique IF NOT EXISTS
  FOR (p:Person) REQUIRE p.name IS UNIQUE;

Irodori-specific behavior

• Object browser mapping (neo4j.rs::metadata): node labels are shown as “tables” and relationship types as “views”. Their “columns” are the property keys, sampled with MATCH (n:\Label`) UNWIND keys(n) AS key RETURN DISTINCT key LIMIT 100`. This is a sampling pass, so a property that only appears on a few nodes can be missed — treat the column list as representative, not exhaustive.
• Results are tabular today. Node/relationship records show as JSON property cells. A query-result graph visualization is a planned shared capability (P1, see docs/data-source-coverage-strategy.md → Graph), not yet in the UI.
• No SQL. Engines like advanced filters / inline editing that assume relational semantics do not apply; use Cypher SET / MERGE / DELETE.

Gotchas

• Use parameters ($name) instead of string-building queries — safer and lets the planner cache the plan.
• MATCH ... DELETE fails if the node still has relationships; use DETACH DELETE.
• Backtick labels/types with special characters: :`Order Line`.
• MERGE matches on the whole pattern — MERGE (p:Person {name:'Ada', born:1815}) with a different born creates a second node. Merge on the key, then SET.
• Bolt over TLS needs the +s scheme (bolt+s:// / neo4j+s://).

Related: Memgraph

Memgraph speaks Bolt + Cypher and is in the DbEngine enum (memgraph) but is currently “recognized, no connector” — most of this page applies once it is routed through the Neo4j/Bolt adapter and verified.

Sources

Generated from knowledge/sources.json:

• neo4j-cypher-manual — https://neo4j.com/docs/cypher-manual/current/
• neo4j-browser-docs — https://neo4j.com/docs/browser/