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26.12.5.1 The events_stages_current Table
The events_stages_current
table
contains current stage events. The table stores one row per
thread showing the current status of the thread's most recent
monitored stage event, so there is no system variable for
configuring the table size.
Of the tables that contain stage event rows,
events_stages_current
is the most
fundamental. Other tables that contain stage event rows are
logically derived from the current events. For example, the
events_stages_history
and
events_stages_history_long
tables
are collections of the most recent stage events that have
ended, up to a maximum number of rows per thread and globally
across all threads, respectively.
For more information about the relationship between the three stage event tables, see Section 26.9, “Performance Schema Tables for Current and Historical Events”.
For information about configuring whether to collect stage events, see Section 26.12.5, “Performance Schema Stage Event Tables”.
The events_stages_current
table
has these columns:
THREAD_ID
,EVENT_ID
The thread associated with the event and the thread current event number when the event starts. The
THREAD_ID
andEVENT_ID
values taken together uniquely identify the row. No two rows have the same pair of values.END_EVENT_ID
This column is set to
NULL
when the event starts and updated to the thread current event number when the event ends.EVENT_NAME
The name of the instrument that produced the event. This is a
NAME
value from thesetup_instruments
table. Instrument names may have multiple parts and form a hierarchy, as discussed in Section 26.6, “Performance Schema Instrument Naming Conventions”.SOURCE
The name of the source file containing the instrumented code that produced the event and the line number in the file at which the instrumentation occurs. This enables you to check the source to determine exactly what code is involved.
TIMER_START
,TIMER_END
,TIMER_WAIT
Timing information for the event. The unit for these values is picoseconds (trillionths of a second). The
TIMER_START
andTIMER_END
values indicate when event timing started and ended.TIMER_WAIT
is the event elapsed time (duration).If an event has not finished,
TIMER_END
is the current timer value andTIMER_WAIT
is the time elapsed so far (TIMER_END
−TIMER_START
).If an event is produced from an instrument that has
TIMED = NO
, timing information is not collected, andTIMER_START
,TIMER_END
, andTIMER_WAIT
are allNULL
.For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 26.4.1, “Performance Schema Event Timing”.
WORK_COMPLETED
,WORK_ESTIMATED
These columns provide stage progress information, for instruments that have been implemented to produce such information.
WORK_COMPLETED
indicates how many work units have been completed for the stage, andWORK_ESTIMATED
indicates how many work units are expected for the stage. For more information, see Stage Event Progress Information.NESTING_EVENT_ID
The
EVENT_ID
value of the event within which this event is nested. The nesting event for a stage event is usually a statement event.NESTING_EVENT_TYPE
The nesting event type. The value is
TRANSACTION
,STATEMENT
,STAGE
, orWAIT
.
The events_stages_current
table
has these indexes:
Primary key on (
THREAD_ID
,EVENT_ID
)
TRUNCATE TABLE
is permitted for
the events_stages_current
table.
It removes the rows.
Document created the 26/06/2006, last modified the 26/10/2018
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