Hi Oleg,

commit 812f8cbfb3a7a02705f65d8bb7e30ae2faf13b5d Author: Oleg Smirnov <olernov@gmail.com> Date: Tue Jun 21 16:20:17 2022 +0700

MDEV-28881 Server crashes in Dep_analysis_context::create_table_value

SELECT_LEX::first_select()->join may be NULL for some scenarios. This commit adds a check for this.

Looking into Jira I can infer that the patch fixes two issues, but the commit comment doesn't say that. Please avoid doing this in the future. Please split the commit into two: - first one fixing the SELECT_LEX::first_select()->join == NULL part - the second fixing the memory management. For the second part, I think it's not a good approach when most of the Table Elimination data resides in a MEM_ROOT with exception of std::set which keeps its data on the heap. I was wondering if there's a way to get STL containers to reside on MEM_ROOT as well, and found that yes there is, and MySQL actually already has it: https://dev.mysql.com/worklog/task/?id=6074 https://github.com/mysql/mysql-server/blob/8.0/sql/mem_root_allocator.h Can we copy mem_root_allocator.h from them (in a separate commit) and then fix memory management here by making std::set use it? BR Sergei -- Sergei Petrunia, Software Developer MariaDB Corporation | Skype: sergefp | Blog: http://petrunia.net