Fix unique constraint checks

Reviewers: mferencevic, teon.banek

Reviewed By: teon.banek

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1680

src/storage/single_node/indexes/label_property_index.hpp

@@ -553,10 +553,17 @@ class LabelPropertyIndex {
                              const Vertex *const vertex) {
     auto access = index.access();
     auto it = access.find_or_larger(IndexEntry{value, nullptr, nullptr});
-    if (it == access.end() || (IndexEntry::Less(it->value_, value) &&
+
-                               IndexEntry::Less(value, it->value_)))
+    // If not found.
+    if (it == access.end()) {
       return true;
-    return false;
+    }
+    // If not equal.
+    if (IndexEntry::Less(it->value_, value) ||
+        IndexEntry::Less(value, it->value_)) {
+      return true;
+    }
+    return vlist->cypher_id() == it->vlist_->cypher_id();
   }
 
   /**

tests/unit/graph_db_accessor_index_api.cpp

@@ -441,3 +441,14 @@ TEST_F(GraphDbAccessorIndex, UniqueConstraintViolationOnBuild) {
   EXPECT_THROW(dba->BuildIndex(label, property, true),
                database::IndexConstraintViolationException);
 }
+
+TEST_F(GraphDbAccessorIndex, UniqueConstraintUpdateProperty) {
+  dba->BuildIndex(label, property, true);
+  AddVertex(0);
+  auto vertex_accessor = dba->InsertVertex();
+  vertex_accessor.add_label(label);
+  vertex_accessor.PropsSet(property, 10);
+
+  EXPECT_THROW(vertex_accessor.PropsSet(property, 0),
+               database::IndexConstraintViolationException);
+}