Undirected query for multi-labelled and unlabelled nodes.

src/binder/bind/bind_graph_pattern.cpp

@@ -27,9 +27,35 @@ Binder::bindGraphPattern(const std::vector<std::unique_ptr<PatternElement>>& gra
     return std::make_pair(std::move(queryGraphCollection), std::move(propertyCollection));
 }
 
+// For undirected pattern (A)-[R]-(B), we need to match R in both FWD and BWD direction.
+// Since computation always starts from one node, we need to rewrite the node table names to be
+// the union of both node table names, i.e. (A|B)-[R]-(A|B)
+void static rewriteNodeTableNameForUndirectedRel(const PatternElement& patternElement) {
+    auto leftNode = patternElement.getFirstNodePattern();
+    for (auto i = 0u; i < patternElement.getNumPatternElementChains(); ++i) {
+        auto patternElementChain = patternElement.getPatternElementChain(i);
+        auto rightNode = patternElementChain->getNodePattern();
+        if (patternElementChain->getRelPattern()->getDirection() == ArrowDirection::BOTH) {
+            std::vector<std::string> tableNameUnion = {};
+            auto leftTableNames = leftNode->getTableNames();
+            auto rightTableNames = rightNode->getTableNames();
+            if (!leftTableNames.empty() && !rightTableNames.empty()) {
+                tableNameUnion.insert(
+                    tableNameUnion.end(), leftTableNames.begin(), leftTableNames.end());
+                tableNameUnion.insert(
+                    tableNameUnion.end(), rightTableNames.begin(), rightTableNames.end());
+            }
+            leftNode->setTableNames(tableNameUnion);
+            rightNode->setTableNames(tableNameUnion);
+        }
+        leftNode = rightNode;
+    }
+}
+
 // Grammar ensures pattern element is always connected and thus can be bound as a query graph.
 std::unique_ptr<QueryGraph> Binder::bindPatternElement(
     const PatternElement& patternElement, PropertyKeyValCollection& collection) {
+    rewriteNodeTableNameForUndirectedRel(patternElement);
     auto queryGraph = std::make_unique<QueryGraph>();
     auto leftNode = bindQueryNode(*patternElement.getFirstNodePattern(), *queryGraph, collection);
     for (auto i = 0u; i < patternElement.getNumPatternElementChains(); ++i) {

src/include/parser/query/graph_pattern/node_pattern.h

@@ -30,6 +30,10 @@ class NodePattern {
             propertyKeyValPairs[idx].first, propertyKeyValPairs[idx].second.get());
     }
 
+    void setTableNames(std::vector<std::string> otherTableNames) {
+        tableNames = std::move(otherTableNames);
+    }
+
 protected:
     std::string variableName;
     std::vector<std::string> tableNames;

test/test_files/demo_db/demo_db.test

@@ -234,3 +234,20 @@ Karissa|30
 Zhang|30
 Zhang|40
 Noura|50
+
+-NAME Undir2
+-QUERY MATCH (a:User)-[:LivesIn]-(c:City) RETURN a.name, c.name;
+---- 8
+Adam|Waterloo
+Karissa|Waterloo
+Zhang|Kitchener
+Noura|Guelph
+Waterloo|Karissa
+Waterloo|Adam
+Kitchener|Zhang
+Guelph|Noura
+
+-NAME Undir3
+-QUERY MATCH ()-[]-() RETURN COUNT(*);
+---- 1
+16

test/test_files/tinysnb/match/undirected.test

@@ -19,3 +19,41 @@ Alice|Dan
 Carol|Dan
 Alice|Dan
 Carol|Dan
+
+-NAME UndirMultiLabel1
+-QUERY MATCH (a:person:organisation)-[:meets|:marries|:workAt]-(b:person:organisation) RETURN COUNT(*);
+---- 1
+26
+
+-NAME UndirMultiLabel2
+-QUERY MATCH (a:person)-[:studyAt|:meets]-(b:person:organisation) RETURN COUNT(*);
+---- 1
+20
+
+-NAME UndirMultiLabel3
+-QUERY MATCH (a:person)-[:meets|:marries|:knows]-(b:person)-[:knows|:meets]-(c:person) WHERE c.fName = "Farooq" AND a.fName <> "Farooq" RETURN a.fName, b.fName;
+---- 13
+Carol|Elizabeth
+Alice|Carol
+Bob|Carol
+Dan|Carol
+Elizabeth|Carol
+Greg|Carol
+Greg|Elizabeth
+Carol|Elizabeth
+Alice|Carol
+Bob|Carol
+Dan|Carol
+Elizabeth|Carol
+Dan|Carol
+
+-NAME UndirUnlabelled
+-QUERY MATCH (a:person)-[]-() RETURN COUNT(*);
+---- 1
+60
+
+-NAME UndirPattern
+-QUERY MATCH ()-[:studyAt]-(a)-[:meets]-()-[:workAt]-() RETURN a.fName;
+---- 2
+Farooq
+Bob