fix bug and update benchmark

benchmarks/db_bench.cc

@@ -74,7 +74,7 @@ static int FLAGS_reads = -1;
 static int FLAGS_threads = 1;
 
 // Size of each value
-static int FLAGS_value_size = 100;
+static int FLAGS_value_size = 5000;
 
 // Arrange to generate values that shrink to this fraction of
 // their original size after compression

db/db_impl.cc

@@ -1234,7 +1234,7 @@ Status DBImpl::Get(const ReadOptions& options, const Slice& key,
   mem->Unref();
   if (imm != nullptr) imm->Unref();
   current->Unref();
-
+  if(!s.ok())return s;
   if(value->c_str()[0]==0x00){
     *value=value->substr(1);
     return s;