fix #2578 (#2591)

Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

core/src/server/delivery/request/SearchCombineRequest.cpp

@@ -384,14 +384,6 @@ SearchCombineRequest::OnExecute() {
             return status;
         }
 
-        // avoid memcpy crash, check id count = target vector count * topk
-        if (result_ids.size() != total_count * search_topk_) {
-            status = Status(DB_ERROR, "Result count doesn't match target vectors count");
-            // let all request return
-            FreeRequests(status);
-            return status;
-        }
-
         // avoid memcpy crash, check distance count = id count
         if (result_distances.size() != result_ids.size()) {
             status = Status(DB_ERROR, "Result distance and id count doesn't match");
@@ -401,18 +393,26 @@ SearchCombineRequest::OnExecute() {
         }
 
         // step 5: construct result array
+        // engine ensure each target vector has same count of id/distance pairs
+        size_t pair_each_vector = result_ids.size() / vectors_data_.vector_count_;
         offset = 0;
         for (auto& request : request_list_) {
             uint64_t count = request->VectorsData().vector_count_;
             int64_t topk = request->TopK();
-            uint64_t element_cnt = count * topk;
+            uint64_t pair_cnt = (pair_each_vector > topk) ? topk : pair_each_vector;
             TopKQueryResult& result = request->QueryResult();
             result.row_num_ = count;
-            result.id_list_.resize(element_cnt);
-            result.distance_list_.resize(element_cnt);
-            memcpy(result.id_list_.data(), result_ids.data() + offset, element_cnt * sizeof(int64_t));
-            memcpy(result.distance_list_.data(), result_distances.data() + offset, element_cnt * sizeof(float));
-            offset += (count * search_topk_);
+            result.id_list_.resize(count * pair_cnt);
+            result.distance_list_.resize(count * pair_cnt);
+
+            for (uint64_t i = 0; i < count; i++) {
+                uint64_t poz = i * pair_cnt;
+                memcpy(result.id_list_.data() + poz, result_ids.data() + offset + poz, pair_cnt * sizeof(int64_t));
+                memcpy(result.distance_list_.data() + poz, result_distances.data() + offset + poz,
+                       pair_cnt * sizeof(float));
+            }
+
+            offset += count * pair_cnt;
 
             // let request return
             FreeRequest(request, Status::OK());