Hi, i did some test about performance schema sql in mariadb 10.1.13
I think that mariadb has erase .frm file about pfs(performance_shcema) since version 10.1.13
but that point is some problem i think below test case.
1) start mysqld (or mysqld_safe) : Mariadb start
2) Sql run : select * from PERFORMANCE_SCHEMA.xxx ( NOT use performance_schema before)
=> Error Occur! : ERROR 1939 (HY000): Engine PERFORMANCE_SCHEMA failed to discover table
=> i think than error happen in function (sql_cache.cc :640 line open_table_def(thd, share, flags | GTS_USE_DISCOVERY)
IF you use "use performance_schema" statement before sql run, that's ok
because i think "use pfs" is load table definition info to cache, so skip "open_table_def" function.
open_table_def fuuction finally search .frm file .. but pfs is no have .frm file since 10.1.13
So, Any Idea about loading pfs schema tables definition to cache during start mariadb (ex: background thread run "use pfs" ?!, or anything ..)
or other plan about this ?