diff --git a/internal/core/src/common/Utils.h b/internal/core/src/common/Utils.h
index bd3216ac2b..301590b9fc 100644
--- a/internal/core/src/common/Utils.h
+++ b/internal/core/src/common/Utils.h
@@ -12,6 +12,7 @@
 #pragma once
 
 #include <google/protobuf/text_format.h>
+
 #include <string>
 
 #include "common/Consts.h"
@@ -85,14 +86,14 @@ PostfixMatch(const std::string& str, const std::string& postfix) {
 inline int64_t
 upper_align(int64_t value, int64_t align) {
     Assert(align > 0);
-    auto groups = (value + align - 1) / align;
+    auto groups = value / align + (value % align != 0);
     return groups * align;
 }
 
 inline int64_t
 upper_div(int64_t value, int64_t align) {
     Assert(align > 0);
-    auto groups = (value + align - 1) / align;
+    auto groups = value / align + (value % align != 0);
     return groups;
 }
 
diff --git a/internal/core/src/segcore/ConcurrentVector.cpp b/internal/core/src/segcore/ConcurrentVector.cpp
index 4d383c1c74..d13748d01e 100644
--- a/internal/core/src/segcore/ConcurrentVector.cpp
+++ b/internal/core/src/segcore/ConcurrentVector.cpp
@@ -109,10 +109,16 @@ VectorBase::fill_chunk_data(ssize_t element_count, const DataArray* data, const
             return fill_chunk_data(data->scalars().double_data().data().data(), element_count);
         }
         case DataType::VARCHAR: {
-            auto begin = data->scalars().string_data().data().begin();
-            auto end = data->scalars().string_data().data().end();
-            std::vector<std::string> data_raw(begin, end);
-            return fill_chunk_data(data_raw.data(), element_count);
+            auto vec = static_cast<ConcurrentVector<std::string>*>(this);
+            auto count = data->scalars().string_data().data().size();
+            vec->grow_on_demand(count);
+            auto& chunk = vec->get_chunk(0);
+
+            size_t index = 0;
+            for (auto& str : data->scalars().string_data().data()) {
+                chunk[index++] = str;
+            }
+            return;
         }
         default: {
             PanicInfo("unsupported");
diff --git a/internal/core/src/segcore/ConcurrentVector.h b/internal/core/src/segcore/ConcurrentVector.h
index b824aa21df..3670d8840e 100644
--- a/internal/core/src/segcore/ConcurrentVector.h
+++ b/internal/core/src/segcore/ConcurrentVector.h
@@ -11,18 +11,18 @@
 
 #pragma once
 
+#include <tbb/concurrent_vector.h>
+
 #include <atomic>
 #include <cassert>
 #include <deque>
 #include <mutex>
+#include <shared_mutex>
 #include <string>
 #include <unordered_map>
-#include <shared_mutex>
 #include <utility>
 #include <vector>
 
-#include <tbb/concurrent_vector.h>
-
 #include "common/FieldMeta.h"
 #include "common/Span.h"
 #include "common/Types.h"
@@ -148,6 +148,12 @@ class ConcurrentVectorImpl : public VectorBase {
         chunks_.emplace_to_at_least(chunk_count, Dim * size_per_chunk_);
     }
 
+    void
+    grow_on_demand(int64_t element_count) {
+        auto chunk_count = upper_div(element_count, size_per_chunk_);
+        chunks_.emplace_to_at_least(chunk_count, Dim * element_count);
+    }
+
     Span<TraitType>
     get_span(int64_t chunk_id) const {
         auto& chunk = get_chunk(chunk_id);
@@ -224,6 +230,11 @@ class ConcurrentVectorImpl : public VectorBase {
         return chunks_[chunk_index];
     }
 
+    Chunk&
+    get_chunk(ssize_t index) {
+        return chunks_[index];
+    }
+
     const void*
     get_chunk_data(ssize_t chunk_index) const override {
         return chunks_[chunk_index].data();
@@ -274,7 +285,7 @@ class ConcurrentVectorImpl : public VectorBase {
             return;
         }
         auto chunk_max_size = chunks_.size();
-        Assert(chunk_id < chunk_max_size);
+        AssertInfo(chunk_id < chunk_max_size, "chunk_id=" + std::to_string(chunk_id));
         Chunk& chunk = chunks_[chunk_id];
         auto ptr = chunk.data();
         std::copy_n(source + source_offset * Dim, element_count * Dim, ptr + chunk_offset * Dim);