select * from performance_schema.events_waits_current
where event_name like 'Wait/Synch/%' limit 1;
select * from performance_schema.events_waits_current
where event_name='FOO';
insert into performance_schema.events_waits_current
set thread_id='1', event_id=1,
event_name='FOO', timer_start=1, timer_end=2, timer_wait=3;
ERROR 42000: INSERT command denied to user 'root'@'localhost' for table 'events_waits_current'
update performance_schema.events_waits_current
set timer_start=12;
ERROR 42000: UPDATE command denied to user 'root'@'localhost' for table 'events_waits_current'
update performance_schema.events_waits_current
set timer_start=12 where thread_id=0;
ERROR 42000: UPDATE command denied to user 'root'@'localhost' for table 'events_waits_current'
delete from performance_schema.events_waits_current
where thread_id=1;
ERROR 42000: DELETE command denied to user 'root'@'localhost' for table 'events_waits_current'
delete from performance_schema.events_waits_current;
ERROR 42000: DELETE command denied to user 'root'@'localhost' for table 'events_waits_current'
LOCK TABLES performance_schema.events_waits_current READ;
ERROR 42000: SELECT, LOCK TABLES command denied to user 'root'@'localhost' for table 'events_waits_current'
UNLOCK TABLES;
LOCK TABLES performance_schema.events_waits_current WRITE;
ERROR 42000: SELECT, LOCK TABLES command denied to user 'root'@'localhost' for table 'events_waits_current'
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='events_waits_current';
column_name	column_comment
THREAD_ID	Thread associated with the event. Together with EVENT_ID uniquely identifies the row.
EVENT_ID	Thread's current event number at the start of the event. Together with THREAD_ID uniquely identifies the row.
END_EVENT_ID	NULL when the event starts, set to the thread's current event number at the end of the event.
EVENT_NAME	Event instrument name and a NAME from the setup_instruments table
SOURCE	Name and line number of the source file containing the instrumented code that produced the event.
TIMER_START	Value in picoseconds when the event timing started or NULL if timing is not collected.
TIMER_END	Value in picoseconds when the event timing ended, or NULL if the event has not ended or timing is not collected.
TIMER_WAIT	Value in picoseconds of the event's duration or NULL if the event has not ended or timing is not collected.
SPINS	Number of spin rounds for a mutex, or NULL if spin rounds are not used, or spinning is not instrumented.
OBJECT_SCHEMA	Name of the schema that contains the table for table I/O objects, otherwise NULL for file I/O and synchronization objects.
OBJECT_NAME	File name for file I/O objects, table name for table I/O objects, the socket's IP:PORT value for a socket object or NULL for a synchronization object.
INDEX_NAME	Name of the index, PRIMARY for the primary key, or NULL for no index used.
OBJECT_TYPE	FILE for a file object, TABLE or TEMPORARY TABLE for a table object, or NULL for a synchronization object.
OBJECT_INSTANCE_BEGIN	Address in memory of the object.
NESTING_EVENT_ID	EVENT_ID of event within which this event nests.
NESTING_EVENT_TYPE	Nesting event type. Either statement, stage or wait.
OPERATION	Operation type, for example read, write or lock
NUMBER_OF_BYTES	Number of bytes that the operation read or wrote, or NULL for table I/O waits.
FLAGS	Reserved for use in the future.