HelixDB Docs

Guide

Traversal operations consume the current stream and produce the next stream.

Operation	Result
`out(label)`	Destination nodes of outgoing edges
`in(label)`	Source nodes of incoming edges
`both(label)`	Adjacent nodes in either direction
`outE(label)` / `inE(label)`	The edges themselves
`outN()` / `inN()`	Move from an edge to its endpoint
`dedup()`	Remove duplicate results

Follow a named result

read_batch()
    .var_as(
        "user",
        g().n_where(SourcePredicate::eq("username", "alice")),
    )
    .var_as(
        "friends",
        g()
            .n(NodeRef::var("user"))
            .out(Some("FOLLOWS"))
            .dedup()
            .limit(25)
            .value_map(Some(vec!["$id", "username"])),
    )
    .returning(["friends"]);

readBatch()
  .varAs("user", g().nWhere(SourcePredicate.eq("username", "alice")))
  .varAs(
    "friends",
    g()
      .n(NodeRef.var("user"))
      .out("FOLLOWS")
      .dedup()
      .limit(25)
      .valueMap(["$id", "username"]),
  )
  .returning(["friends"]);

helix.ReadQuery("friends").
	VarAs("user", helix.G().NWhere(helix.SourceEq("username", "alice"))).
	VarAs(
		"friends",
		helix.G().
			N(helix.NodeVar("user")).
			Out("FOLLOWS").
			Dedup().
			Limit(25).
			ValueMap("$id", "username"),
	).
	Returning("friends")

(
    read_batch()
    .var_as("user", g().n_where(SourcePredicate.eq("username", "alice")))
    .var_as(
        "friends",
        g()
        .n(NodeRef.var("user"))
        .out("FOLLOWS")
        .dedup()
        .limit(25)
        .value_map(["$id", "username"]),
    )
    .returning(["friends"])
)

{
  "request_type": "read",
  "query_name": "friends",
  "query": {
    "read": {
      "entries": [
        {
          "query": {
            "name": "user",
            "root": {
              "nodes_where": {
                "predicate": {
                  "eq": {
                    "left": { "property": "username" },
                    "right": { "constant": { "string": "alice" } }
                  }
                }
              }
            }
          }
        },
        {
          "query": {
            "name": "friends",
            "root": {
              "value_map": {
                "input": {
                  "limit": {
                    "input": {
                      "dedup": {
                        "input": {
                          "out": {
                            "input": {
                              "nodes": {
                                "reference": { "var": "user" }
                              }
                            },
                            "label": "FOLLOWS"
                          }
                        }
                      }
                    },
                    "count": { "literal": 25 }
                  }
                },
                "properties": ["$id", "username"]
              }
            }
          }
        }
      ],
      "returns": ["friends"]
    }
  }
}

Preserve correlated values

Use bind when a result row must retain values from multiple points in one traversal: Bind the starting service as service, traverse ROUTES_TO, bind the result as workload, then project both bindings with projectDistinctBindings (or the language-equivalent builder). Bindings are row-local. Branches can bind optional values and coalesce them during projection without joining unrelated paths.

Avoid accidental path growth

Filter as close to the source as possible.
Use a label on relationship steps when the schema provides one.
Add dedup() when multiple paths can reach the same entity.
Bound recursive traversal with a maximum depth.
Project only the fields needed by the caller.

Start Here

Core Concepts

Query Guides

Traverse relationships

Follow a named result

Preserve correlated values

Avoid accidental path growth

Next steps

Project response rows

Branch and repeat

​Follow a named result

​Preserve correlated values

​Avoid accidental path growth

​Next steps

Project response rows

Branch and repeat

Follow a named result

Preserve correlated values

Avoid accidental path growth

Next steps