select * from performance_schema.hosts
limit 1;
select * from performance_schema.hosts
where host='FOO';
insert into performance_schema.hosts
set host='FOO',
current_connections=1, total_connections=2;
ERROR 42000: INSERT command denied to user 'root'@'localhost' for table `performance_schema`.`hosts`
update performance_schema.hosts
set current_connections=12;
ERROR 42000: UPDATE command denied to user 'root'@'localhost' for table `performance_schema`.`hosts`
update performance_schema.hosts
set current_connections=12 where host like "FOO";
ERROR 42000: UPDATE command denied to user 'root'@'localhost' for table `performance_schema`.`hosts`
delete from performance_schema.hosts
where total_connections=1;
ERROR 42000: DELETE command denied to user 'root'@'localhost' for table `performance_schema`.`hosts`
delete from performance_schema.hosts;
ERROR 42000: DELETE command denied to user 'root'@'localhost' for table `performance_schema`.`hosts`
LOCK TABLES performance_schema.hosts READ;
ERROR 42000: SELECT, LOCK TABLES command denied to user 'root'@'localhost' for table `performance_schema`.`hosts`
UNLOCK TABLES;
LOCK TABLES performance_schema.hosts WRITE;
ERROR 42000: SELECT, LOCK TABLES command denied to user 'root'@'localhost' for table `performance_schema`.`hosts`
UNLOCK TABLES;
#
# MDEV-25325 column_comment for performance_schema tables
#
select column_name, column_comment 
from information_schema.columns 
where table_schema='performance_schema' and table_name='hosts';
column_name	column_comment
HOST	Host name used by the client to connect, NULL for internal threads or user sessions that failed to authenticate.
CURRENT_CONNECTIONS	Current number of the host's connections.
TOTAL_CONNECTIONS	Total number of the host's connections