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OpenCypher Tests

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The tests validate OpenCypher query support and common graph patterns.

They also include regression coverage for planner behavior that matters to the Python bindings, such as UNWIND variables being usable inside WHERE predicates.

OpenCypher

OpenCypher is a declarative graph query language for pattern matching and traversal.

import arcadedb_embedded as arcadedb

with arcadedb.create_database("./opencypher_test_db") as db:
    db.command("sql", "CREATE VERTEX TYPE Person")
    db.command("sql", "CREATE EDGE TYPE Knows UNIDIRECTIONAL")

    with db.transaction():
        alice = db.new_vertex("Person")
        alice.set("name", "Alice").save()

        bob = db.new_vertex("Person")
        bob.set("name", "Bob").save()

        edge = alice.new_edge("Knows", bob)
        edge.save()

    result = db.query("opencypher", """
        MATCH (p:Person)-[:Knows]->(friend:Person)
        RETURN friend.name as name
    """)

    names = [r.get("name") for r in result]
    assert "Bob" in names

Running This Test

pytest tests/test_cypher.py -v

Notable Regression Coverage

  • UNWIND variables can be referenced from WHERE clauses during MATCH
  • Aggregations on missing labels still return a single row with 0
  • Result property order remains stable for projected OpenCypher values

OpenCypher vs SQL MATCH

Feature SQL MATCH OpenCypher
Style SQL-like Declarative graph patterns
Focus Set operations + graph patterns Pattern matching + paths
Learning curve Easier if you know SQL Easier if you know Cypher
Graph traversal Strong Strong

Example Comparison

SQL MATCH: 

MATCH {type: Person, as: p}-Knows->{type: Person, as: friend}
RETURN friend.name

OpenCypher: 

MATCH (p:Person)-[:Knows]->(friend:Person)
RETURN friend.name