From a4d78682ff650e6ea5086357e708bb8a3e70e109 Mon Sep 17 00:00:00 2001
From: lihangyu <15605149486@163.com>
Date: Fri, 17 Nov 2023 10:18:21 +0800
Subject: [PATCH] [Optimize](point query) clear names to reduce mem consumption
 and cpu cost related to block column name (#26931)

---
 be/src/service/point_query_executor.cpp | 3 ++-
 be/src/vec/core/block.cpp               | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/be/src/service/point_query_executor.cpp b/be/src/service/point_query_executor.cpp
index 580e0b66df..12e1f9f677 100644
--- a/be/src/service/point_query_executor.cpp
+++ b/be/src/service/point_query_executor.cpp
@@ -48,7 +48,7 @@
 namespace doris {
 
 Reusable::~Reusable() {}
-constexpr static int s_preallocted_blocks_num = 64;
+constexpr static int s_preallocted_blocks_num = 32;
 Status Reusable::init(const TDescriptorTable& t_desc_tbl, const std::vector<TExpr>& output_exprs,
                       size_t block_size) {
     SCOPED_MEM_COUNT_BY_HOOK(&_mem_size);
@@ -334,6 +334,7 @@ Status PointQueryExecutor::_lookup_row_data() {
 template <typename MysqlWriter>
 Status _serialize_block(MysqlWriter& mysql_writer, vectorized::Block& block,
                         PTabletKeyLookupResponse* response) {
+    block.clear_names();
     RETURN_IF_ERROR(mysql_writer.append_block(block));
     assert(mysql_writer.results().size() == 1);
     uint8_t* buf = nullptr;
diff --git a/be/src/vec/core/block.cpp b/be/src/vec/core/block.cpp
index 5f1dc7f512..779f214c97 100644
--- a/be/src/vec/core/block.cpp
+++ b/be/src/vec/core/block.cpp
@@ -178,6 +178,9 @@ void Block::insert(size_t position, ColumnWithTypeAndName&& elem) {
 
 void Block::clear_names() {
     index_by_name.clear();
+    for (auto& entry : data) {
+        entry.name.clear();
+    }
 }
 
 void Block::insert(const ColumnWithTypeAndName& elem) {