diff --git a/include/rabitqlib/index/estimator.hpp b/include/rabitqlib/index/estimator.hpp
index b3f87ec..05bc47b 100644
--- a/include/rabitqlib/index/estimator.hpp
+++ b/include/rabitqlib/index/estimator.hpp
@@ -31,24 +31,60 @@ inline void split_batch_estdist(
     float* ip_x0_qr,
     bool use_hacc
 ) {
+    constexpr size_t kSafeChunkDim = 1024;
     ConstBatchDataMap<float> cur_batch(batch_data, padded_dim);
     RowMajorArray<int32_t> accu_arr(1, fastscan::kBatchSize);
 
     if (use_hacc) {
         std::array<int32_t, fastscan::kBatchSize> accu_res;
-        fastscan::accumulate_hacc(
-            cur_batch.bin_code(), q_obj.lut(), accu_res.data(), padded_dim
-        );
         for (size_t i = 0; i < fastscan::kBatchSize; ++i) {
-            accu_arr.data()[i] = accu_res[i];
+            accu_arr.data()[i] = 0;
+        }
+
+        const uint8_t* codes_ptr =
+            reinterpret_cast<const uint8_t*>(cur_batch.bin_code());
+        const uint8_t* lut_ptr = reinterpret_cast<const uint8_t*>(q_obj.lut());
+        size_t remaining_dim = padded_dim;
+
+        while (remaining_dim > kSafeChunkDim) {
+            fastscan::accumulate_hacc(
+                codes_ptr, lut_ptr, accu_res.data(), kSafeChunkDim
+            );
+            codes_ptr += kSafeChunkDim << 2;
+            lut_ptr += kSafeChunkDim << 3;
+            for (size_t i = 0; i < fastscan::kBatchSize; ++i) {
+                accu_arr.data()[i] += accu_res[i];
+            }
+            remaining_dim -= kSafeChunkDim;
+        }
+
+        fastscan::accumulate_hacc(codes_ptr, lut_ptr, accu_res.data(), remaining_dim);
+        for (size_t i = 0; i < fastscan::kBatchSize; ++i) {
+            accu_arr.data()[i] += accu_res[i];
         }
     } else {
         std::array<uint16_t, fastscan::kBatchSize> accu_res;
-        fastscan::accumulate(
-            cur_batch.bin_code(), q_obj.lut(), accu_res.data(), padded_dim
-        );
+        const uint8_t* codes_ptr =
+            reinterpret_cast<const uint8_t*>(cur_batch.bin_code());
+        const uint8_t* lut_ptr = reinterpret_cast<const uint8_t*>(q_obj.lut());
         for (size_t i = 0; i < fastscan::kBatchSize; ++i) {
-            accu_arr.data()[i] = accu_res[i];
+            accu_arr.data()[i] = 0;
+        }
+
+        size_t remaining_dim = padded_dim;
+        while (remaining_dim > kSafeChunkDim) {
+            fastscan::accumulate(codes_ptr, lut_ptr, accu_res.data(), kSafeChunkDim);
+            codes_ptr += kSafeChunkDim << 2;
+            lut_ptr += kSafeChunkDim << 2;
+            for (size_t i = 0; i < fastscan::kBatchSize; ++i) {
+                accu_arr.data()[i] += accu_res[i];
+            }
+            remaining_dim -= kSafeChunkDim;
+        }
+
+        fastscan::accumulate(codes_ptr, lut_ptr, accu_res.data(), remaining_dim);
+        for (size_t i = 0; i < fastscan::kBatchSize; ++i) {
+            accu_arr.data()[i] += accu_res[i];
         }
     }
 
@@ -70,6 +106,7 @@ inline void split_batch_estdist(
     low_dist_arr = est_dist_arr - f_error_arr * q_obj.g_error();
 }
 
+
 /**
  * @brief Use ex-data bits to get more accurate distance
  *
@@ -188,4 +225,4 @@ inline void split_single_estdist(
     low_dist = est_dist - (cur_bin.f_error() * g_error);
 };
 
-}  // namespace rabitqlib
\ No newline at end of file
+}  // namespace rabitqlib