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lvcalvca
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fix: cypher Dijkstra return
Fixed Issue #4042
1 parent 82808c2 commit 9f01ab6

2 files changed

Lines changed: 175 additions & 11 deletions

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‎engine/src/main/java/com/arcadedb/query/opencypher/procedures/algo/AlgoDijkstra.java‎

Lines changed: 33 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -18,6 +18,7 @@
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*/
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package com.arcadedb.query.opencypher.procedures.algo;
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import com.arcadedb.database.Database;
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import com.arcadedb.database.RID;
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import com.arcadedb.graph.Edge;
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import com.arcadedb.graph.Vertex;
@@ -26,6 +27,7 @@
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import com.arcadedb.query.sql.executor.ResultInternal;
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import com.arcadedb.function.sql.graph.SQLFunctionAstar;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.LinkedList;
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import java.util.List;
@@ -102,23 +104,43 @@ public Stream<Result> execute(final Object[] args, final Result inputRow, final
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if (pathRids == null || pathRids.isEmpty())
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return Stream.empty();
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// Calculate total weight
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// The A* implementation returns vertices only. Traverse the edges between consecutive
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// vertices to reconstruct the path's total weight and to expose the relationships.
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final Database db = context.getDatabase();
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final Vertex.DIRECTION dir = parseDirection(direction);
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final String[] edgeTypeFilter = relType != null && !relType.isEmpty() ? new String[] { relType } : null;
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final List<RID> pathWithEdges = new ArrayList<>(pathRids.size() * 2 - 1);
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pathWithEdges.add(pathRids.get(0));
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double totalWeight = 0.0;
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for (int i = 0; i < pathRids.size() - 1; i++) {
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final RID current = pathRids.get(i);
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final var currentDoc = context.getDatabase().lookupByRID(current, true);
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// If this is an edge, get its weight
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if (currentDoc.getRecord() instanceof Edge edge) {
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final Object weight = edge.get(weightProperty);
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if (weight instanceof Number num) {
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totalWeight += num.doubleValue();
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final Vertex from = pathRids.get(i).asVertex();
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final RID toRid = pathRids.get(i + 1);
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Edge bestEdge = null;
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double bestWeight = Double.POSITIVE_INFINITY;
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for (final Edge edge : edgeTypeFilter != null ? from.getEdges(dir, edgeTypeFilter) : from.getEdges(dir)) {
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final RID otherRid = edge.getOut().equals(from.getIdentity()) ? edge.getIn() : edge.getOut();
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if (!toRid.equals(otherRid))
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continue;
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final Object w = edge.get(weightProperty);
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final double edgeWeight = w instanceof Number num ? num.doubleValue() : 0.0;
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if (edgeWeight < bestWeight) {
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bestWeight = edgeWeight;
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bestEdge = edge;
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}
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}
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if (bestEdge != null) {
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totalWeight += bestWeight;
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pathWithEdges.add(bestEdge.getIdentity());
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}
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pathWithEdges.add(toRid);
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}
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120-
// Build path representation
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final Map<String, Object> path = buildPath(pathRids, context.getDatabase());
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// Build path representation including edges
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final Map<String, Object> path = buildPath(pathWithEdges, db);
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final ResultInternal result = new ResultInternal();
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result.setProperty("path", path);

‎engine/src/test/java/com/arcadedb/query/opencypher/procedures/algo/AlgoDijkstraTest.java‎

Lines changed: 142 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,142 @@
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/*
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* Copyright © 2021-present Arcade Data Ltd ([email protected])
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* SPDX-FileCopyrightText: 2021-present Arcade Data Ltd ([email protected])
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* SPDX-License-Identifier: Apache-2.0
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*/
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package com.arcadedb.query.opencypher.procedures.algo;
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import com.arcadedb.database.Database;
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import com.arcadedb.database.DatabaseFactory;
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import com.arcadedb.graph.MutableVertex;
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import com.arcadedb.graph.Vertex;
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import com.arcadedb.query.sql.executor.Result;
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import com.arcadedb.query.sql.executor.ResultSet;
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import org.junit.jupiter.api.AfterEach;
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import org.junit.jupiter.api.BeforeEach;
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import org.junit.jupiter.api.Test;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Map;
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import static org.assertj.core.api.Assertions.assertThat;
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/**
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* Tests for the algo.dijkstra Cypher procedure.
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*
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* Regression for issue #4042: yielded weight was always 0 because the path returned by the
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* underlying A* implementation only contains vertex RIDs, not edges. Weight must be reconstructed
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* by traversing the edges between consecutive vertices on the path.
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*
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* @author Luca Garulli ([email protected])
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*/
46+
class AlgoDijkstraTest {
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private Database database;
48+
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@BeforeEach
50+
void setup() {
51+
final DatabaseFactory factory = new DatabaseFactory("./target/databases/test-algo-dijkstra");
52+
if (factory.exists())
53+
factory.open().drop();
54+
database = factory.create();
55+
database.getSchema().createVertexType("Node");
56+
database.getSchema().createEdgeType("Road");
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// Start --2--> Middle --3--> Finish
59+
database.transaction(() -> {
60+
final MutableVertex start = database.newVertex("Node").set("name", "Start").save();
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final MutableVertex middle = database.newVertex("Node").set("name", "Middle").save();
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final MutableVertex finish = database.newVertex("Node").set("name", "Finish").save();
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start.newEdge("Road", middle, true, new Object[] { "distance", 2 }).save();
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middle.newEdge("Road", finish, true, new Object[] { "distance", 3 }).save();
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});
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}
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@AfterEach
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void teardown() {
70+
if (database != null)
71+
database.drop();
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}
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@Test
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void dijkstraComputesCorrectWeight() {
76+
final ResultSet rs = database.query("opencypher",
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"""
78+
MATCH (src:Node {name:'Start'}),(dst:Node {name:'Finish'}) \
79+
CALL algo.dijkstra(src, dst, 'Road', 'distance') \
80+
YIELD path, weight RETURN weight""");
81+
82+
assertThat(rs.hasNext()).isTrue();
83+
final Result result = rs.next();
84+
final Object weight = result.getProperty("weight");
85+
assertThat(weight).isInstanceOf(Number.class);
86+
assertThat(((Number) weight).doubleValue()).isEqualTo(5.0);
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}
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89+
@Test
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void dijkstraPathIncludesEdges() {
91+
final ResultSet rs = database.query("opencypher",
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"""
93+
MATCH (src:Node {name:'Start'}),(dst:Node {name:'Finish'}) \
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CALL algo.dijkstra(src, dst, 'Road', 'distance') \
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YIELD path, weight RETURN path, weight""");
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97+
assertThat(rs.hasNext()).isTrue();
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final Result result = rs.next();
99+
@SuppressWarnings("unchecked")
100+
final Map<String, Object> path = (Map<String, Object>) result.getProperty("path");
101+
assertThat(path).isNotNull();
102+
103+
final List<?> nodes = (List<?>) path.get("nodes");
104+
final List<?> relationships = (List<?>) path.get("relationships");
105+
assertThat(nodes).hasSize(3);
106+
assertThat(relationships).hasSize(2);
107+
}
108+
109+
@Test
110+
void dijkstraStartEqualsEnd() {
111+
final ResultSet rs = database.query("opencypher",
112+
"""
113+
MATCH (src:Node {name:'Start'}) \
114+
CALL algo.dijkstra(src, src, 'Road', 'distance') \
115+
YIELD path, weight RETURN weight""");
116+
117+
assertThat(rs.hasNext()).isTrue();
118+
final Result result = rs.next();
119+
assertThat(((Number) result.getProperty("weight")).doubleValue()).isEqualTo(0.0);
120+
}
121+
122+
@Test
123+
void dijkstraMultiHopAccumulatesWeight() {
124+
// Add a fourth hop: Finish --4--> End
125+
database.transaction(() -> {
126+
final Vertex finish = database.query("sql",
127+
"SELECT FROM Node WHERE name='Finish'").next().getElement().get().asVertex();
128+
final MutableVertex end = database.newVertex("Node").set("name", "End").save();
129+
finish.modify().newEdge("Road", end, true, new Object[] { "distance", 4 }).save();
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});
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132+
final ResultSet rs = database.query("opencypher",
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"""
134+
MATCH (src:Node {name:'Start'}),(dst:Node {name:'End'}) \
135+
CALL algo.dijkstra(src, dst, 'Road', 'distance') \
136+
YIELD path, weight RETURN weight""");
137+
138+
assertThat(rs.hasNext()).isTrue();
139+
final Result result = rs.next();
140+
assertThat(((Number) result.getProperty("weight")).doubleValue()).isEqualTo(9.0);
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}
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}

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