From 2092dc0ba1910a560b5cd2c79fcef3b302f2a752 Mon Sep 17 00:00:00 2001
From: Gao <chao.gao@zilliz.com>
Date: Thu, 31 Oct 2024 10:02:21 +0800
Subject: [PATCH] enhance: reserve vector space to reduce reallocate cost in
 Views() and StringViews() (#37182)

issue: #37152

Signed-off-by: chasingegg <chao.gao@zilliz.com>
---
 internal/core/src/mmap/Column.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/internal/core/src/mmap/Column.h b/internal/core/src/mmap/Column.h
index 698097d306..2800d849d5 100644
--- a/internal/core/src/mmap/Column.h
+++ b/internal/core/src/mmap/Column.h
@@ -682,6 +682,7 @@ class SingleChunkVariableColumn : public SingleChunkColumnBase {
     std::pair<std::vector<std::string_view>, FixedVector<bool>>
     StringViews() const override {
         std::vector<std::string_view> res;
+        res.reserve(num_rows_);
         char* pos = data_;
         for (size_t i = 0; i < num_rows_; ++i) {
             uint32_t size;
@@ -696,6 +697,7 @@ class SingleChunkVariableColumn : public SingleChunkColumnBase {
     [[nodiscard]] std::vector<ViewType>
     Views() const {
         std::vector<ViewType> res;
+        res.reserve(num_rows_);
         char* pos = data_;
         for (size_t i = 0; i < num_rows_; ++i) {
             uint32_t size;