| name | gql-path-patterns |
| description | Use when building or debugging variable-length paths, reachability, shortest/cheapest path, or fan-out control in GQL/Cypher-like graph queries. Triggers: variable-length path, reachability, DEPENDS_ON walk, path explode, bounded hops. |
| metadata | {"pattern":"tool-wrapper","specialization":"graph-paths","domain":"data","version":"1.1"} |
| token_guardrails | - Always bound hop depth (e.g. {1,4}); never bare unbounded walks by default.
- Anchor at least one endpoint with label + selective property.
- Prefer DISTINCT + LIMIT when projecting nodes from fan-out paths.
|
GQL Path Patterns
Thin skill for paths and reachability. Pair with graph-query-language for basics.
Rules of thumb
- Bound every variable-length hop (
{1,3} not bare *).
- Anchor at least one end with label + selective property.
- Prefer typed relationships (
:REL) over untyped walks.
- Decide directed vs undirected before writing the pattern.
Bounded walk
MATCH (start:System { id: $id })-[:DEPENDS_ON]->{1,4}(dep:System)
RETURN DISTINCT dep.id AS dependency
LIMIT 200
Exists / reachability
MATCH (a:Node { id: $a })
FILTER EXISTS {
MATCH (a)-[:LINK]->{1,6}(b:Node { id: $b })
}
RETURN a.id AS reachable_from
(If EXISTS subquery is unsupported, use a bounded MATCH + count(*) > 0.)
Fan-out control
- Filter early (
FILTER / WHERE on start node).
- Constrain rel types.
- Cap depth.
DISTINCT + LIMIT on projection.- For analytics, aggregate (
count, collect) instead of returning every path.
Path objects
MATCH p = (a:Person)-[:KNOWS]->{1,3}(b:Person)
FILTER a.id = $a AND b.id = $b
RETURN p
LIMIT 20
Return nodes/rels extracted from p if the client cannot render path values.
Common failure modes
| Symptom | Likely cause |
|---|
| Timeout / OOM | Unbounded depth or missing labels |
| Empty result | Wrong direction or tighter type than data |
| Duplicate rows | Missing DISTINCT on node projection |
| Wrong end node | Undirected pattern absorbing reverse edges |
Deliverable style
Give the bounded query first. State max depth and relationship types assumed. Add a stricter variant if the first is for exploration.
Related
