From 28602d36254263127c0e1b90334614abc1ee0c83 Mon Sep 17 00:00:00 2001
From: wzk784533 <wzk784533@163.com>
Date: Sat, 11 Jul 2020 13:44:11 +0800
Subject: [PATCH] avoid unnecessary memory copy

---
 db/builder.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/db/builder.cc b/db/builder.cc
index 943e857..fe5cde1 100644
--- a/db/builder.cc
+++ b/db/builder.cc
@@ -30,11 +30,14 @@ Status BuildTable(const std::string& dbname, Env* env, const Options& options,
 
     TableBuilder* builder = new TableBuilder(options, file);
     meta->smallest.DecodeFrom(iter->key());
+    Slice key;
     for (; iter->Valid(); iter->Next()) {
-      Slice key = iter->key();
-      meta->largest.DecodeFrom(key);
+      key = iter->key();
       builder->Add(key, iter->value());
     }
+    if(!key.empty()) {
+      meta->largest.DecodeFrom(key);
+    }
 
     // Finish and check for builder errors
     s = builder->Finish();