select * from performance_schema.file_instances limit 1;
select * from performance_schema.file_instances
where file_name='FOO';
insert into performance_schema.file_instances
set file_name='FOO', event_name='BAR', open_count=12;
ERROR 42000: INSERT command denied to user 'root'@'localhost' for table `performance_schema`.`file_instances`
update performance_schema.file_instances
set file_name='FOO';
ERROR 42000: UPDATE command denied to user 'root'@'localhost' for table `performance_schema`.`file_instances`
delete from performance_schema.file_instances
where event_name like "wait/%";
ERROR 42000: DELETE command denied to user 'root'@'localhost' for table `performance_schema`.`file_instances`
delete from performance_schema.file_instances;
ERROR 42000: DELETE command denied to user 'root'@'localhost' for table `performance_schema`.`file_instances`
LOCK TABLES performance_schema.file_instances READ;
ERROR 42000: SELECT, LOCK TABLES command denied to user 'root'@'localhost' for table `performance_schema`.`file_instances`
UNLOCK TABLES;
LOCK TABLES performance_schema.file_instances WRITE;
ERROR 42000: SELECT, LOCK TABLES command denied to user 'root'@'localhost' for table `performance_schema`.`file_instances`
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='file_instances';
column_name	column_comment
FILE_NAME	File name.
EVENT_NAME	Instrument name associated with the file.
OPEN_COUNT	Open handles on the file. A value of greater than zero means that the file is currently open.