examples · graph · 2 / 7

2. reverse - one-hop inbound adjacency

what this does

Who points at this row? reverse is the mirror of neighbors - same relation, opposite direction. Given the primary key of a target row, returns the array of primary keys that have an edge pointing to it.

when to use it

"Which orders bought this product?" - the inverse of the forward query.
Anywhere you would scan a table to find rows whose foreign key matches a value.
Building inbound feeds, audit trails, "referenced by" panels.

schema requirement

The relation must be declared with bidirectional = true - which is the default. If a relation is one-way only, reverse on it returns 400. See schemas/reference#relations.

the request

GET /v1/tenants/:t/graph/:schema/reverse?rel=...&pk=...

curl "https://$OC_HOST/v1/tenants/$OC_TENANT/graph/shop.orders/reverse?rel=bought_product&pk=p001" \
  -H "Authorization: Bearer $OC_TOKEN"

result = db.graph.reverse(
    "shop.orders",
    rel="bought_product",
    pk="p001",
)

const result = await db.graph.reverse("shop.orders", {
  rel: "bought_product",
  pk: "p001",
});

result, _ := db.Graph().Reverse(ctx, "shop.orders", originchain.ReverseRequest{
    Rel: "bought_product",
    PK:  "p001",
})

what you get back

[
  "o001",
  "o042",
  "o118"
]

A flat array of source primary keys. Same shape as neighbors, just walking the other direction.

how it works

When the relation is bidirectional, the write path lays down a second adjacency entry keyed by the target.
reverse is then a point lookup against that inbound entry - identical cost profile to neighbors.
The cost is the price of bidirectionality: storage roughly doubles for the edge, but reads stay O(fan-in).

common mistakes

Relation set to bidirectional = false. reverse refuses to run. Re-declare the relation or use forward traversal from the other side.
High fan-in nodes. A "popular" product can have hundreds of thousands of inbound edges. Paginate at the call site or use pagerank when you want ranked influence rather than the raw list.