table contains current transaction events. The table stores
one row per thread showing the current status of the thread's
most recent monitored transaction event, so there is no system
variable for configuring the table size. For example:
mysql> SELECT * FROM performance_schema.events_transactions_current LIMIT 1\G *************************** 1. row *************************** THREAD_ID: 26 EVENT_ID: 7 END_EVENT_ID: NULL EVENT_NAME: transaction STATE: ACTIVE TRX_ID: NULL GTID: 3E11FA47-71CA-11E1-9E33-C80AA9429562:56 XID: NULL XA_STATE: NULL SOURCE: transaction.cc:150 TIMER_START: 420833537900000 TIMER_END: NULL TIMER_WAIT: NULL ACCESS_MODE: READ WRITE ISOLATION_LEVEL: REPEATABLE READ AUTOCOMMIT: NO NUMBER_OF_SAVEPOINTS: 0 NUMBER_OF_ROLLBACK_TO_SAVEPOINT: 0 NUMBER_OF_RELEASE_SAVEPOINT: 0 OBJECT_INSTANCE_BEGIN: NULL NESTING_EVENT_ID: 6 NESTING_EVENT_TYPE: STATEMENT
Of the tables that contain transaction event rows,
the most fundamental. Other tables that contain transaction
event rows are logically derived from the current events. For
tables are collections of the most recent transaction 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 transaction event tables, see Performance Schema Tables for Current and Historical Events.
For information about configuring whether to collect transaction events, see Section 10.7, “Performance Schema Transaction Tables”.
table has these columns:
The thread associated with the event and the thread current event number when the event starts. The
EVENT_IDvalues taken together uniquely identify the row. No two rows have the same pair of values.
This column is set to
NULLwhen the event starts and updated to the thread current event number when the event ends.
The name of the instrument from which the event was collected. This is a
NAMEvalue from the
setup_instrumentstable. Instrument names may have multiple parts and form a hierarchy, as discussed in Chapter 7, Performance Schema Instrument Naming Conventions.
The current transaction state. The value is
The GTID column contains the value of
gtid_next, which can be one of
AUTOMATIC, or a GTID using the format
UUID:NUMBER. For transactions that use
gtid_next=AUTOMATIC, which is all normal client transactions, the GTID column changes when the transaction commits and the actual GTID is assigned. If
ON_PERMISSIVE, the GTID column changes to the transaction's GTID. If
OFF_PERMISSIVE, the GTID column changes to
The elements of the XA transaction identifier. They have the format described in XA Transaction SQL Statements.
The state of the XA transaction. The value is
XA ROLLBACK), or
On a replica, the same XA transaction can appear in the
events_transactions_currenttable with different states on different threads. This is because immediately after the XA transaction is prepared, it is detached from the replication applier thread, and can be committed or rolled back by any thread on the replica. The
events_transactions_currenttable displays the current status of the most recent monitored transaction event on the thread, and does not update this status when the thread is idle. So the XA transaction can still be displayed in the
PREPAREDstate for the original applier thread, after it has been processed by another thread. To positively identify XA transactions that are still in the
PREPAREDstate and need to be recovered, use the
XA RECOVERstatement rather than the Performance Schema transaction tables.
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.
Timing information for the event. The unit for these values is picoseconds (trillionths of a second). The
TIMER_ENDvalues indicate when event timing started and ended.
TIMER_WAITis the event elapsed time (duration).
If an event has not finished,
TIMER_ENDis the current timer value and
TIMER_WAITis the time elapsed so far (
If an event is produced from an instrument that has
TIMED = NO, timing information is not collected, and
For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 5.1, “Performance Schema Event Timing”.
The transaction access mode. The value is
The transaction isolation level. The value is
READ UNCOMMITTED, or
Whether autcommit mode was enabled when the transaction started.
The number of
ROLLBACK TO SAVEPOINT, and
RELEASE SAVEPOINTstatements issued during the transaction.
EVENT_IDvalue of the event within which this event is nested.
The nesting event type. The value is
TRANSACTIONdoes not appear because transactions cannot be nested.)
TRUNCATE TABLE is permitted for
table. It removes the rows.