MDEV-33881 Userstat skips system tables inconsistently

Fixed that no tables from 'mysql' schema are included in userstat.
A beneif of this is that the server is not reading statistics tables
if mysql.proc or other tables in mysql is accessed.

mysql-test/main/mysqldump-system,win.rdiff

 --- mysqldump-system.result
 +++ mysqldump-system,win.result
-@@ -449,9 +449,9 @@
+@@ -1861,9 +1861,9 @@
  Table	Checksum
  mysql.roles_mapping	2510045525
  mysql.time_zone_transition	3719776009
@@ -9,10 +9,10 @@
  mysql.servers	2079085450
 -mysql.func	3241572444
 +mysql.func	310494789
- mysql.innodb_table_stats	1285726777
- mysql.table_stats	2836905944
+ mysql.innodb_table_stats	1972297402
+ mysql.table_stats	1911089388
  # Opps....
-@@ -484,9 +484,9 @@
+@@ -1896,9 +1896,9 @@
  Table	Checksum
  mysql.roles_mapping	2510045525
  mysql.time_zone_transition	3719776009
@@ -21,6 +21,6 @@
  mysql.servers	2079085450
 -mysql.func	3241572444
 +mysql.func	310494789
- mysql.innodb_table_stats	1285726777
- mysql.table_stats	2836905944
+ mysql.innodb_table_stats	1972297402
+ mysql.table_stats	1911089388
  DROP FUNCTION IF EXISTS metaphon;

mysql-test/main/mysqldump-system.test

@@ -39,18 +39,18 @@ ALTER TABLE mysql.roles_mapping ORDER BY Host, User, Role;
 # innodb and EITS tables statistics
 #
 set @save_innodb_stats_persistent= @@innodb_stats_persistent;
-create table mysql.tz like mysql.time_zone_transition;
-alter table mysql.tz engine=innodb;
-insert into mysql.tz select * from mysql.time_zone_transition;
+create table test.tz like mysql.time_zone_transition;
+alter table test.tz engine=innodb;
+insert into test.tz select * from mysql.time_zone_transition;
 set global innodb_stats_persistent=1;
 set time_zone="+03:00";
 SET TIMESTAMP= UNIX_TIMESTAMP('2022-01-07 07:07:00');
-ANALYZE TABLE mysql.tz PERSISTENT FOR ALL;
+ANALYZE TABLE test.tz PERSISTENT FOR ALL;
 # for predictable output in tests
 delete from mysql.index_stats where prefix_arity!=1;
 delete from mysql.column_stats where column_name!='Time_zone_id';
-update mysql.innodb_index_stats set last_update="2020-01-01" where database_name="mysql" and table_name="tz";
-update mysql.innodb_table_stats set last_update="2020-01-01" where database_name="mysql" and table_name="tz";
+update mysql.innodb_index_stats set last_update="2020-01-01" where database_name="test" and table_name="tz";
+update mysql.innodb_table_stats set last_update="2020-01-01" where database_name="test" and table_name="tz";
 update mysql.column_stats set histogram=json_replace(histogram, '$.collected_by', replace(json_value(histogram, '$.collected_by'), @@version, 'version'));
 set global innodb_stats_persistent= @save_innodb_stats_persistent;
 alter table mysql.time_zone_name ORDER BY Name;
@@ -144,12 +144,12 @@ DROP FUNCTION IF EXISTS metaphon;
 DROP SERVER s1;
 
 # EITS && innodb stats
-DELETE FROM mysql.column_stats WHERE db_name='mysql' and table_name in ('tz', 'gtid_slave_pos');
-DELETE FROM mysql.index_stats  WHERE db_name='mysql' and table_name in ('tz', 'gtid_slave_pos');
-DELETE FROM mysql.table_stats  WHERE db_name='mysql' and table_name in ('tz', 'gtid_slave_pos');
-DELETE FROM mysql.innodb_index_stats WHERE database_name='mysql' and table_name in ('tz','gtid_slave_pos');
-DELETE FROM mysql.innodb_table_stats WHERE database_name='mysql' and table_name in ('tz','gtid_slave_pos');
-drop table mysql.tz;
+DELETE FROM mysql.column_stats WHERE db_name='mysql';
+DELETE FROM mysql.index_stats  WHERE db_name='mysql';
+DELETE FROM mysql.table_stats  WHERE db_name='mysql';
+DELETE FROM mysql.innodb_index_stats WHERE database_name='test';
+DELETE FROM mysql.innodb_table_stats WHERE database_name='mysql';
+drop table test.tz;
 
 DROP ROLE role_2;
 DROP ROLE role_1;

mysql-test/main/ps.result

@@ -2145,11 +2145,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 call proc_1();
 show open tables from mysql;
@@ -2159,11 +2156,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 call proc_1();
 show open tables from mysql;
@@ -2173,11 +2167,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 call proc_1();
 show open tables from mysql;
@@ -2187,11 +2178,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 flush tables;
 create function func_1() returns int begin flush tables; return 1; end|
@@ -2206,11 +2194,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 prepare abc from "flush tables";
 execute abc;
@@ -2221,11 +2206,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 execute abc;
 show open tables from mysql;
@@ -2235,11 +2217,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 execute abc;
 show open tables from mysql;
@@ -2249,11 +2228,8 @@ select Host, User from mysql.user limit 0;
 Host	User
 show open tables from mysql;
 Database	Table	In_use	Name_locked
-mysql	column_stats	0	0
 mysql	general_log	0	0
 mysql	global_priv	0	0
-mysql	index_stats	0	0
-mysql	table_stats	0	0
 mysql	user	0	0
 flush tables;
 deallocate prepare abc;

mysql-test/main/userstat.result

@@ -240,12 +240,18 @@ set @@global.general_log=@save_general_log;
 #
 create function f() returns int return (select 1 from performance_schema.threads);
 set global userstat= 1;
+create table t1 (a int primary key);
+insert into t1 values (1),(2);
+select * from t1 where a=1;
+a
+1
 select f() from information_schema.table_statistics;
 ERROR 21000: Subquery returns more than 1 row
 select f() from information_schema.index_statistics;
 ERROR 21000: Subquery returns more than 1 row
 set global userstat= 0;
 drop function f;
+drop table t1;
 #
 # End of 10.2 tests
 #

mysql-test/main/userstat.test

@@ -122,12 +122,16 @@ set @@global.general_log=@save_general_log;
 --echo #
 create function f() returns int return (select 1 from performance_schema.threads);
 set global userstat= 1;
+create table t1 (a int primary key);
+insert into t1 values (1),(2);
+select * from t1 where a=1;
 --error ER_SUBQUERY_NO_1_ROW
 select f() from information_schema.table_statistics;
 --error ER_SUBQUERY_NO_1_ROW
 select f() from information_schema.index_statistics;
 set global userstat= 0;
 drop function f;
+drop table t1;
 --enable_ps2_protocol
 
 --echo #
@@ -145,7 +149,9 @@ set global userstat= 1;
 create or replace table t1 (a int, key(a)) engine=MyISAM;
 insert into t1 values (1),(2),(3),(4);
 flush index_statistics;
+--disable_ps2_protocol
 select a from t1 where a in ( select a from t1 );
+--enable_ps2_protocol
 show index_statistics;
 drop table t1;
 set global userstat=@save_userstat;

sql/sql_base.cc

@@ -2312,7 +2312,8 @@ bool open_table(THD *thd, TABLE_LIST *table_list, Open_table_context *ot_ctx)
     */
     enum enum_mdl_type mdl_type= MDL_BACKUP_DML;
 
-    if (table->s->table_category != TABLE_CATEGORY_USER)
+    if (table->s->table_category != TABLE_CATEGORY_USER &&
+        table->s->table_category != TABLE_CATEGORY_MYSQL)
       mdl_type= MDL_BACKUP_SYS_DML;
     else if (table->s->online_backup)
       mdl_type= MDL_BACKUP_TRANS_DML;

sql/table.cc

@@ -324,6 +324,8 @@ TABLE_CATEGORY get_table_category(const Lex_ident_db &db,
         name.streq(SLOW_LOG_NAME) ||
         name.streq(TRANSACTION_REG_NAME))
       return TABLE_CATEGORY_LOG;
+
+    return TABLE_CATEGORY_MYSQL;
   }
 
   return TABLE_CATEGORY_USER;

sql/table.h

@@ -490,6 +490,11 @@ enum enum_table_category
   */
   TABLE_CATEGORY_LOG=5,
 
+  /**
+     Other tables in the mysql schema, like global_priv and db
+  */
+  TABLE_CATEGORY_MYSQL= 6,
+
   /*
     Types below are read only tables, not affected by FLUSH TABLES or
     MDL locks.
@@ -514,7 +519,7 @@ enum enum_table_category
     to I_S tables in the table cache, which should use
     this table type.
   */
-  TABLE_CATEGORY_INFORMATION=6,
+  TABLE_CATEGORY_INFORMATION=7,
 
   /**
     Performance schema tables.
@@ -536,7 +541,7 @@ enum enum_table_category
     The server implementation perform writes.
     Performance tables are cached in the table cache.
   */
-  TABLE_CATEGORY_PERFORMANCE=7
+  TABLE_CATEGORY_PERFORMANCE=8
 };
 
 typedef enum enum_table_category TABLE_CATEGORY;