SSSP

SQL function: cugraph_sssp

Official cuGraph reference: C API

Compute minimum weighted-path distances and predecessors from one source vertex to every reachable vertex.

Signature

cugraph_sssp(table_name, source_vertex [, src_col, dst_col [, weight_col [, options_json]]])

Relation inputs

The first positional argument names a registered edge table or view (the edges role). Parenthesized relation subqueries are not accepted; metadata validation uses the same registered name.

Vertex ID types

The edges relation declares the accepted vertex-ID domains. Numeric calls preserve the existing numeric schema. When logical string support is declared, Utf8, LargeUtf8, and Utf8View endpoint columns share one logical domain; their vertex-identity outputs are canonicalized to Utf8.

Domain	Accepted endpoint inputs	Output contract
Numeric edge endpoints	Int32, Int64	The numeric output schema is used for numeric calls.
Logical string edge endpoints	Utf8, LargeUtf8, Utf8View	Vertex identity columns are canonicalized to Utf8; scores, distances, counts, coordinates, and opaque labels remain numeric.

The native mapping type is Int64. Call-specific output schemas come from gpu_validate_call.

Logical string side-input limitations:

• edge ID columns and edge-ID predicate side inputs are not supported for logical string graphs

Scalar arguments & JSON options

Positional scalar arguments

src_col and dst_col name the edge endpoint columns; both are optional and default to src and dst.

Argument	Type	Required	Default	Notes
source_vertex	Int64|Utf8	yes
weight_col	Utf8|null	no		optional edge weight column for graph construction when supported by the algorithm; semantic effect: edge weights affect algorithm results when provided

JSON options

Option	Type	Default	Constraints	Description
cutoff	Float64|null	null	min 0

Graph construction options

Graph construction follows the shared defaults (directed=true, renumbering, python_cugraph policy) documented in Graph Construction Options.

Output schema

Column	Type	Nullable	Description
vertex	Int64|Utf8	no	Vertex reached by the shortest-path traversal.
distance	Float64	no	Shortest weighted-path distance from the source vertex.
predecessor	Int64|Utf8	yes	Previous vertex on the shortest-path tree, null for the source or unreachable vertices.

These are generic descriptor schemas; validate the call to get the concrete, table-specific output schema.

Examples

This example runs on the citation network demo dataset.

SQL-derived edge weights

The citation edges carry a constant weight, but the weight column handed to SSSP can be computed by SQL. Joining papers on both endpoints prices each citation hop at the number of years it spans, so SSSP distance becomes the cumulative year span along the cheapest reference chain:

CREATE VIEW edges_time_cost AS
SELECT e.src, e.dst,
       CAST(GREATEST(1, ps.year - pd.year) AS DOUBLE) AS weight
FROM citation_edges e
JOIN papers ps ON ps.paper_id = e.src
JOIN papers pd ON pd.paper_id = e.dst
WHERE ps.year > 1900 AND pd.year > 1900;

SELECT CAST(ROUND(s.distance) AS BIGINT) AS time_cost, p.year, p.title
FROM cugraph_sssp('edges_time_cost', 2963403868, 'src', 'dst', 'weight') s
JOIN papers p ON p.paper_id = s.vertex
WHERE s.distance < 1e300
ORDER BY p.year ASC, s.distance ASC
LIMIT 6;

time_cost	year	title
84	1933	Algebraic Functions
82	1935	When is a Trigonometric Polynomial Not a Trigonometric Polynomial
81	1936	Correction to a Note on the Entscheidungsproblem
81	1936	Toward a Calculus of Concepts
81	1936	Set-Theoretic Foundations for Logic
81	1936	A System of Formal Logic without an Analogue to the Curry W. Operator

Starting from Attention Is All You Need (2017), the cheapest reference chains reach the 1936 foundations of computability and formal logic at a time-cost of 81 years. The GREATEST(1, …) clamp keeps weights positive (same-year and forward-dated citations cost 1), and the WHERE clause drops the handful of bogus pre-1900 years in the source data. Unreached vertices report an infinite distance, filtered here with s.distance < 1e300.

Limitations & lifecycle

No algorithm-specific limitations.

Validate before running

Dry-run validation checks registered relation metadata, column presence, static dtypes, and options only; it does not scan edge data, construct a graph, or prove source-vertex existence:

SELECT * FROM gpu_validate_call(
  'cugraph_sssp',
  '{"schema_version":1,"relations":{"edges":{"table":"target_edges"}},"options":{"source_vertex":123,"src_col":"src","dst_col":"dst"}}'
);

See GPU Function Catalog API for the full gpu_validate_call contract.