support build one point graph in odescent

Signed-off-by: jinjiabao.jjb <jinjiabao.jjb@antgroup.com>
antgroup · Feb 5, 2025 · fa770fb · fa770fb
1 parent 11f89df
commit fa770fb
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Showing 3 changed files with 24 additions and 9 deletions.
diff --git a/src/data_cell/sparse_graph_datacell.cpp b/src/data_cell/sparse_graph_datacell.cpp
@@ -42,6 +42,7 @@ SparseGraphDataCell::InsertNeighborsById(InnerIdType id, const Vector<InnerIdTyp
     this->max_capacity_ = std::max(this->max_capacity_, id + 1);
     if (not this->neighbors_.count(id)) {
         this->neighbors_.emplace(id, std::make_unique<Vector<InnerIdType>>(allocator_));
+        this->total_count_ += 1;
     }
     this->neighbors_[id]->assign(neighbor_ids.begin(), neighbor_ids.begin() + size);
 }
@@ -88,6 +89,7 @@ SparseGraphDataCell::Deserialize(StreamReader& reader) {
         this->neighbors_[key] = std::make_unique<vsag::Vector<InnerIdType>>(allocator_);
         StreamReader::ReadVector(reader, *(this->neighbors_[key]));
     }
+    this->total_count_ = size;
 }
 void
 SparseGraphDataCell::Resize(InnerIdType new_size){};

diff --git a/src/impl/odescent_graph_builder.cpp b/src/impl/odescent_graph_builder.cpp
@@ -54,8 +54,11 @@ ODescent::Build(const uint32_t* valid_ids, int64_t data_num) {
     } else {
         data_num_ = flatten_interface_->TotalCount();
     }
-    if (data_num_ <= 1) {
-        throw std::runtime_error("ODescent cannot build a graph with data_num less than 1");
+    if (data_num_ <= 0) {
+        throw std::runtime_error("ODescent cannot build a graph with data_num less than 0");
+    } else if (data_num_ == 1) {
+        graph.push_back(Linklist(allocator_));
+        return true;
     }
     min_in_degree_ = std::min(min_in_degree_, data_num_ - 1);
     Vector<std::mutex>(data_num_, allocator_).swap(points_lock_);
@@ -379,11 +382,14 @@ ODescent::SaveGraph(GraphInterfacePtr& graph_storage) {
             id = valid_ids_[i];
         }
         Vector<uint32_t> edges(allocator_);
-        edges.resize(graph[i].neighbors.size());
-        for (int j = 0; j < graph[i].neighbors.size(); ++j) {
-            edges[j] = graph[i].neighbors[j].id;
-            if (valid_ids_) {
-                edges[j] = valid_ids_[graph[i].neighbors[j].id];
+        size_t size = graph[i].neighbors.size();
+        if (size > 0) {
+            edges.resize(size);
+            for (int j = 0; j < size; ++j) {
+                edges[j] = graph[i].neighbors[j].id;
+                if (valid_ids_) {
+                    edges[j] = valid_ids_[graph[i].neighbors[j].id];
+                }
             }
         }
         graph_storage->InsertNeighborsById(id, edges);

diff --git a/src/impl/odescent_graph_builder_test.cpp b/src/impl/odescent_graph_builder_test.cpp
@@ -96,7 +96,7 @@ TEST_CASE("ODescent Build Test", "[ut][ODescent]") {
             valid_ids[i] = 2 * i;
         }
     }
-    if (num_vectors <= 1) {
+    if (num_vectors <= 0) {
         REQUIRE_THROWS(graph.Build(valid_ids.get(), num_vectors));
         return;
     }
@@ -107,9 +107,16 @@ TEST_CASE("ODescent Build Test", "[ut][ODescent]") {
     graph_interface = vsag::GraphInterface::MakeInstance(graph_param_ptr, param, partial_data);
     graph.SaveGraph(graph_interface);
 
+    auto id_map = [&](uint32_t id) -> uint32_t { return partial_data ? valid_ids[id] : id; };
+
+    if (num_vectors == 1) {
+        REQUIRE(graph_interface->TotalCount() == 1);
+        REQUIRE(graph_interface->GetNeighborSize(id_map(0)) == 0);
+        return;
+    }
+
     float hit_edge_count = 0;
     int64_t indeed_max_degree = std::min(max_degree, (int64_t)num_vectors - 1);
-    auto id_map = [&](uint32_t id) -> uint32_t { return partial_data ? valid_ids[id] : id; };
     for (int i = 0; i < num_vectors; ++i) {
         std::vector<std::pair<float, uint32_t>> ground_truths;
         uint32_t i_id = id_map(i);