commit b550f3b496467b9bdb81cb00d015c9a30d0df93b
Author: zhongbei.yk <zhongbei.yk@alibaba-inc.com>
Date:   Wed May 29 13:32:08 2024 +0800

    Bug #115124 sort file cache is not fully controlled
    
    Description
    ===========
    Sort file cache in DDL is not fully controlled by
    innodb_disable_sort_file_cache.
    
    Analysis
    ========
    There is a temporary file named tmpfd which is used in DDL file-sorting
    is not controlled by innodb_disable_sort_file_cache.
    
    Fix
    ===
    The tmpfd should be controlled by innodb_disable_sort_file_cache.
    I also checked the tmpfd's read and write processes, and the IO
    processes are IO-aligned.

diff --git a/storage/innobase/ddl/ddl0merge.cc b/storage/innobase/ddl/ddl0merge.cc
index b0a0785f970..627bac4259a 100644
--- a/storage/innobase/ddl/ddl0merge.cc
+++ b/storage/innobase/ddl/ddl0merge.cc
@@ -503,6 +503,10 @@ dberr_t Merge_file_sort::sort(Builder *builder,
   auto tmpfd = ddl::file_create_low(builder->tmpdir());
 
   if (tmpfd.is_open()) {
+    if (srv_disable_sort_file_cache) {
+      os_file_set_nocache(tmpfd.get(), "ddl0merge.cc", "sort");
+    }
+
     MONITOR_ATOMIC_INC(MONITOR_ALTER_TABLE_SORT_FILES);
   } else {
     return DB_OUT_OF_RESOURCES;