MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0
The Performance Schema maintains the
objects_summary_global_by_type
table for aggregating object wait events.
Example object wait event summary information:
mysql> SELECT * FROM performance_schema.objects_summary_global_by_type\G
...
*************************** 3. row ***************************
OBJECT_TYPE: TABLE
OBJECT_SCHEMA: test
OBJECT_NAME: t
COUNT_STAR: 3
SUM_TIMER_WAIT: 263126976
MIN_TIMER_WAIT: 1522272
AVG_TIMER_WAIT: 87708678
MAX_TIMER_WAIT: 258428280
...
*************************** 10. row ***************************
OBJECT_TYPE: TABLE
OBJECT_SCHEMA: mysql
OBJECT_NAME: user
COUNT_STAR: 14
SUM_TIMER_WAIT: 365567592
MIN_TIMER_WAIT: 1141704
AVG_TIMER_WAIT: 26111769
MAX_TIMER_WAIT: 334783032
...
The
objects_summary_global_by_type
table has these grouping columns to indicate how the table
aggregates events: OBJECT_TYPE
,
OBJECT_SCHEMA
, and
OBJECT_NAME
. Each row summarizes events for
the given object.
objects_summary_global_by_type
has the same summary columns as the
events_waits_summary_by_
tables. See
Section 29.12.20.1, “Wait Event Summary Tables”.
xxx
The
objects_summary_global_by_type
table has these indexes:
Primary key on (OBJECT_TYPE
,
OBJECT_SCHEMA
,
OBJECT_NAME
)
TRUNCATE TABLE
is permitted for
the object summary table. It resets the summary columns to
zero rather than removing rows.