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/* :file: This file is part of the pgRouting project.
:copyright: Copyright (c) 2025-2026 pgRouting developers
:license: Creative Commons Attribution-Share Alike 3.0 https://creativecommons.org/licenses/by-sa/3.0 */
BEGIN;
UPDATE edges SET cost = sign(cost), reverse_cost = sign(reverse_cost);
SELECT CASE WHEN min_lib_version('3.4.0') THEN plan(8) ELSE plan(7) END;
CREATE OR REPLACE FUNCTION edge_cases()
RETURNS SETOF TEXT AS
$BODY$
BEGIN
IF NOT min_version('3.0.0') THEN
RETURN QUERY
SELECT skip(1, 'Function is new on 3.0.0');
RETURN;
END IF;
-- empty graph
PREPARE q1 AS
SELECT * FROM pgr_topologicalsort(
'SELECT id, source, target, cost, reverse_cost
FROM edges WHERE id > 18'
);
RETURN QUERY
SELECT lives_ok('q1');
RETURN QUERY
SELECT is_empty('q1', 'graph with 0 edge and 0 vertex returns empty');
-- non DAG graph
PREPARE q2 AS
SELECT * FROM pgr_topologicalsort(
'SELECT id, source, target, cost, reverse_cost
FROM edges WHERE id = 7'
);
IF min_lib_version('3.4.0') THEN
/* On v3.4 there is an additional check */
RETURN QUERY SELECT throws_ok('q2', 'Graph is not DAG', 'throws is not DAG error');
END IF;
-- 1 vertex test
PREPARE q3 AS
SELECT * FROM pgr_topologicalsort(
'SELECT id, source, 6 AS target, cost, -1 AS reverse_cost
FROM edges WHERE id = 2'
);
RETURN QUERY
SELECT is_empty('q3', 'graph with one vertex returns empty');
-- 2 vertices test (connected)
PREPARE q4 AS
SELECT * FROM pgr_topologicalsort(
'SELECT id, source, target, cost, -1 AS reverse_cost
FROM edges WHERE id = 7'
);
RETURN QUERY
SELECT set_eq('q4', $$VALUES (1, 3), (2, 7)$$, 'graph with two connected vertices return correct order');
-- 2 vertices test (isolated)
CREATE TABLE two_isolated_vertices_table (
id BIGSERIAL,
source BIGINT,
target BIGINT,
cost FLOAT DEFAULT -1,
reverse_cost FLOAT DEFAULT -1
);
INSERT INTO two_isolated_vertices_table (source, target) VALUES
(2, 2),
(1, 1);
PREPARE q5 AS
SELECT * FROM pgr_topologicalsort(
'SELECT id, source, target, cost, reverse_cost
FROM two_isolated_vertices_table'
);
RETURN QUERY
SELECT is_empty('q5', 'graph with two isolated vertices returns empty');
-- 3 vertices test (a -> b -> c)
PREPARE q6 AS
SELECT * FROM pgr_topologicalsort(
'SELECT id, source, target, 1 AS cost, -1 AS reverse_cost
FROM edges WHERE id <= 2'
);
RETURN QUERY
SELECT set_eq('q6', $$VALUES (1, 5), (2, 6), (3, 10)$$, 'graph with three vertices returns correct order');
-- 3 vertices test (a -> {b, c})
PREPARE q7 AS
SELECT * FROM pgr_topologicalsort(
'SELECT id, source, target, 1 AS cost, -1 AS reverse_cost
FROM edges WHERE source = 10'
);
RETURN QUERY
SELECT set_eq('q7', $$VALUES (1, 10), (2, 15), (3, 11)$$, 'graph with one source and two targets returns correct order');
END
$BODY$
LANGUAGE plpgsql;
SELECT edge_cases();
SELECT * FROM finish();
ROLLBACK;
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