diff --git a/CHANGELOG.md b/CHANGELOG.md
index fa2116a63b..47ab1cb94e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -34,6 +34,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - \#39 - Create SQ8H index hang if using github server version
 - \#30 - Some troubleshoot messages in Milvus do not provide enough information
 - \#48 - Config unittest failed
+- \#59 - Topk result is incorrect for small dataset
 
 ## Improvement
 - MS-552 - Add and change the easylogging library
diff --git a/core/src/index/cmake/ThirdPartyPackagesCore.cmake b/core/src/index/cmake/ThirdPartyPackagesCore.cmake
index ee1d88ee32..99f52dc284 100644
--- a/core/src/index/cmake/ThirdPartyPackagesCore.cmake
+++ b/core/src/index/cmake/ThirdPartyPackagesCore.cmake
@@ -243,7 +243,8 @@ if(CUSTOMIZATION)
         # set(FAISS_MD5 "57da9c4f599cc8fa4260488b1c96e1cc") # commit-id 6dbdf75987c34a2c853bd172ea0d384feea8358c branch-0.2.0
         # set(FAISS_MD5 "21deb1c708490ca40ecb899122c01403") # commit-id 643e48f479637fd947e7b93fa4ca72b38ecc9a39 branch-0.2.0
         # set(FAISS_MD5 "072db398351cca6e88f52d743bbb9fa0") # commit-id 3a2344d04744166af41ef1a74449d68a315bfe17 branch-0.2.1
-        set(FAISS_MD5 "c89ea8e655f5cdf58f42486f13614714") # commit-id 9c28a1cbb88f41fa03b03d7204106201ad33276b branch-0.2.1
+        # set(FAISS_MD5 "c89ea8e655f5cdf58f42486f13614714") # commit-id 9c28a1cbb88f41fa03b03d7204106201ad33276b branch-0.2.1
+        set(FAISS_MD5 "87fdd86351ffcaf3f80dc26ade63c44b") # commit-id 841a156e67e8e22cd8088e1b58c00afbf2efc30b branch-0.2.1
     endif()
 else()
     set(FAISS_SOURCE_URL "https://github.com/facebookresearch/faiss/archive/v1.5.3.tar.gz")
diff --git a/core/src/index/knowhere/knowhere/index/vector_index/IndexIVF.cpp b/core/src/index/knowhere/knowhere/index/vector_index/IndexIVF.cpp
index 0c4856f2b6..fba2e11e2e 100644
--- a/core/src/index/knowhere/knowhere/index/vector_index/IndexIVF.cpp
+++ b/core/src/index/knowhere/knowhere/index/vector_index/IndexIVF.cpp
@@ -24,17 +24,21 @@
 #include <faiss/IndexIVFPQ.h>
 #include <faiss/gpu/GpuAutoTune.h>
 #include <faiss/index_io.h>
+#include <chrono>
 #include <memory>
 #include <utility>
 #include <vector>
 
 #include "knowhere/adapter/VectorAdapter.h"
 #include "knowhere/common/Exception.h"
+#include "knowhere/common/Log.h"
 #include "knowhere/index/vector_index/IndexGPUIVF.h"
 #include "knowhere/index/vector_index/IndexIVF.h"
 
 namespace knowhere {
 
+using stdclock = std::chrono::high_resolution_clock;
+
 IndexModelPtr
 IVF::Train(const DatasetPtr& dataset, const Config& config) {
     auto build_cfg = std::dynamic_pointer_cast<IVFCfg>(config);
@@ -216,7 +220,15 @@ IVF::GenGraph(const int64_t& k, Graph& graph, const DatasetPtr& dataset, const C
 void
 IVF::search_impl(int64_t n, const float* data, int64_t k, float* distances, int64_t* labels, const Config& cfg) {
     auto params = GenParams(cfg);
+    stdclock::time_point before = stdclock::now();
     faiss::ivflib::search_with_parameters(index_.get(), n, (float*)data, k, distances, labels, params.get());
+    stdclock::time_point after = stdclock::now();
+    double search_cost = (std::chrono::duration<double, std::micro>(after - before)).count();
+    KNOWHERE_LOG_DEBUG << "IVF search cost: " << search_cost
+                       << ", quantization cost: " << faiss::indexIVF_stats.quantization_time
+                       << ", data search cost: " << faiss::indexIVF_stats.search_time;
+    faiss::indexIVF_stats.quantization_time = 0;
+    faiss::indexIVF_stats.search_time = 0;
 }
 
 VectorIndexPtr
diff --git a/core/src/scheduler/task/SearchTask.cpp b/core/src/scheduler/task/SearchTask.cpp
index b7a1e211d2..2836d41dd4 100644
--- a/core/src/scheduler/task/SearchTask.cpp
+++ b/core/src/scheduler/task/SearchTask.cpp
@@ -253,7 +253,7 @@ XSearchTask::MergeTopkToResultSet(const std::vector<int64_t>& input_ids, const s
 
         if (result[i].empty()) {
             result_buf.resize(input_k, scheduler::IdDistPair(-1, 0.0));
-            uint64_t input_k_multi_i = input_k * i;
+            uint64_t input_k_multi_i = topk * i;
             for (auto k = 0; k < input_k; ++k) {
                 uint64_t idx = input_k_multi_i + k;
                 auto& result_buf_item = result_buf[k];
@@ -266,7 +266,7 @@ XSearchTask::MergeTopkToResultSet(const std::vector<int64_t>& input_ids, const s
             result_buf.resize(output_k, scheduler::IdDistPair(-1, 0.0));
             size_t buf_k = 0, src_k = 0, tar_k = 0;
             uint64_t src_idx;
-            uint64_t input_k_multi_i = input_k * i;
+            uint64_t input_k_multi_i = topk * i;
             while (buf_k < output_k && src_k < input_k && tar_k < tar_size) {
                 src_idx = input_k_multi_i + src_k;
                 auto& result_buf_item = result_buf[buf_k];