allow 0 as bound node

src/binder/bind/bind_graph_pattern.cpp

@@ -338,11 +338,9 @@ std::pair<uint64_t, uint64_t> Binder::bindVariableLengthRelBound(
             "Lower bound of rel " + relPattern.getVariableName() + " is greater than upperBound.");
     }
     if (upperBound > clientContext->varLengthExtendMaxDepth) {
-        throw BinderException("Upper bound of rel exceeds maximum: " +
-                              std::to_string(clientContext->varLengthExtendMaxDepth) + ".");
-    }
-    if (lowerBound == 0 || upperBound == 0) {
-        throw BinderException("Lower and upper bound of a rel must be greater than 0.");
+        throw BinderException(
+            "Upper bound of rel " + relPattern.getVariableName() +
+            " exceeds maximum: " + std::to_string(clientContext->varLengthExtendMaxDepth) + ".");
     }
     if ((relPattern.getRelType() == QueryRelType::ALL_SHORTEST ||
             relPattern.getRelType() == QueryRelType::SHORTEST) &&

src/processor/operator/recursive_extend/frontier_scanner.cpp

@@ -56,6 +56,12 @@ void DstNodeScanner::scanFromDstOffset(RecursiveJoinVectors* vectors, sel_t& vec
 
 void PathScanner::scanFromDstOffset(RecursiveJoinVectors* vectors, sel_t& vectorPos,
     sel_t& nodeIDDataVectorPos, sel_t& relIDDataVectorPos) {
+    // when bound node is 0
+    if (k == 0) {
+        writePathToVector(vectors, vectorPos, nodeIDDataVectorPos, relIDDataVectorPos);
+        return;
+    }
+
     auto level = 0;
     while (!nbrsStack.empty()) {
         auto& cursor = cursorStack.top();
@@ -87,7 +93,9 @@ void PathScanner::initDfs(const frontier::node_rel_id_t& nodeAndRelID, size_t cu
     nodeIDs[currentDepth] = nodeAndRelID.first;
     relIDs[currentDepth] = nodeAndRelID.second;
     if (currentDepth == 0) {
-        cursorStack.top() = -1;
+        if (k != 0) {
+            cursorStack.top() = -1;
+        }
         return;
     }
     auto nbrs = &frontiers[currentDepth]->bwdEdges.at(nodeAndRelID.first);
@@ -99,7 +107,7 @@ void PathScanner::initDfs(const frontier::node_rel_id_t& nodeAndRelID, size_t cu
 void PathScanner::writePathToVector(RecursiveJoinVectors* vectors, sel_t& vectorPos,
     sel_t& nodeIDDataVectorPos, sel_t& relIDDataVectorPos) {
     assert(vectorPos < DEFAULT_VECTOR_CAPACITY);
-    auto nodeEntry = ListVector::addList(vectors->pathNodesVector, k - 1);
+    auto nodeEntry = ListVector::addList(vectors->pathNodesVector, k ? k - 1 : 0);
     auto relEntry = ListVector::addList(vectors->pathRelsVector, k);
     vectors->pathNodesVector->setValue(vectorPos, nodeEntry);
     vectors->pathRelsVector->setValue(vectorPos, relEntry);

test/test_files/exceptions/binder/binder_error.test

@@ -213,11 +213,6 @@ Binder exception: p1.age has data type INT64. (STRING) was expected.
 ---- error
 Binder exception: Union and union all can't be used together.
 
--LOG VarLenExtendZeroLowerBound
--STATEMENT MATCH (a:person)-[:knows*0..5]->(b:person) return count(*)
----- error
-Binder exception: Lower and upper bound of a rel must be greater than 0.
-
 -LOG ReadAfterUpdate
 -STATEMENT MATCH (a:person) SET a.age = 35 WITH a MATCH (a)-[:knows]->(b:person) RETURN a.age
 ---- error

test/test_files/tck/match/match4.test

@@ -37,7 +37,6 @@
 
 # Zero-length variable length pattern in the middle of the pattern
 -CASE Scenario3
--SKIP
 -STATEMENT CREATE NODE TABLE A(ID SERIAL, name STRING, PRIMARY KEY(ID));
 ---- ok
 -STATEMENT CREATE REL TABLE CONTAIN(FROM A TO A);
@@ -146,7 +145,7 @@
                   (n2)-[:EDGE]->(n3);
 ---- ok
 -STATEMENT MATCH ()-[r:EDGE]-()
-           MATCH p = (n)-[*0..1]-()-[p:EDGE]-()-[*0..1]-(m)
+           MATCH p = (n)-[*0..1]-()-[r:EDGE]-()-[*0..1]-(m)
            RETURN count(p) AS c
 ---- 1
 32

test/test_files/tinysnb/call/call.test

@@ -37,7 +37,7 @@
 10
 -STATEMENT MATCH (a:person)-[:knows*1..28]->(b:person) RETURN COUNT(*);
 ---- error
-Binder exception: Upper bound of rel exceeds maximum: 10.
+Binder exception: Upper bound of rel  exceeds maximum: 10.
 -STATEMENT MATCH (a:person)-[:knows*1..10]->(b:person) RETURN COUNT(*);
 ---- 1
 354290

test/test_files/tinysnb/var_length_extend/range_literal.test

@@ -116,10 +116,50 @@ QueryPlanner::getProperties
 ---- ok
 -STATEMENT MATCH(a:person {fName: "Alice"})-[e:meets*11..23]->(b:person) RETURN b.fName;
 ---- error
-Binder exception: Upper bound of rel exceeds maximum: 10.
+Binder exception: Upper bound of rel e exceeds maximum: 10.
 -STATEMENT MATCH(a:person {fName: "Alice"})-[e:meets*..11]->(b:person) RETURN b.fName;
 ---- error
-Binder exception: Upper bound of rel exceeds maximum: 10.
+Binder exception: Upper bound of rel e exceeds maximum: 10.
 -STATEMENT MATCH(a:person {fName: "Alice"})-[e:meets*11]->(b:person) RETURN b.fName;
 ---- error
-Binder exception: Upper bound of rel exceeds maximum: 10.
+Binder exception: Upper bound of rel e exceeds maximum: 10.
+
+-CASE ZeroBound
+-STATEMENT MATCH(a:person)-[e:knows*0]-() RETURN a.ID;
+---- 8
+0
+2
+3
+5
+7
+8
+9
+10
+-STATEMENT MATCH(a:person {fName: "Alice"})-[e:meets*0..1]->(b:person) RETURN b.fName;
+---- 2
+Alice
+Bob
+-STATEMENT MATCH(a:person {fName: "Alice"})<-[e:meets*0..0]-(b:person) RETURN b.fName;
+---- 1
+Alice
+-STATEMENT MATCH(a:person)-[e:meets*0..0]-(b:person) RETURN b.ID;
+---- 8
+0
+2
+3
+5
+7
+8
+9
+10
+-STATEMENT MATCH(a:person {fName: "Alice"})-[e:meets*0..3]->(b:person) RETURN b.fName;
+---- 3
+Alice
+Bob
+Dan
+-STATEMENT MATCH(a:person {fName: "Alice"})-[e:meets*..0]->(b:person) RETURN b.fName;
+---- error
+Binder exception: Lower bound of rel e is greater than upperBound.
+-STATEMENT MATCH(a:person {fName: "Alice"})-[e:meets*2..0]->(b:person) RETURN b.fName;
+---- error
+Binder exception: Lower bound of rel e is greater than upperBound.