If the slave is not multi-threaded, this table is empty.
Otherwise, the slave uses multiple worker threads and a
coordinator thread to manage them, and this table shows the
status of the worker threads. (For a multi-threaded slave, the
table shows the status of the coordinator thread.) This table
was added in MySQL 5.7.2.
table has these columns:
The worker identifier (same value as the
id column in the
mysql.slave_worker_info table). After
STOP SLAVE, the
THREAD_ID column becomes
NULL, but the
WORKER_ID value is preserved.
The worker thread ID.
ON (thread exists and is active or
OFF (thread no longer exists).
The transaction that the worker has last seen. The worker has not necessarily executed this transaction because it could still be in the process of doing so.
variable value is
OFF, this column is
ANONYMOUS, indicating that transactions
do not have global transaction identifiers (GTIDs) and are
identified by file and position only.
ON, the column value is defined as
If no transaction has executed, the column is empty.
The GTID is preserved until the next transaction is executed. If an error occurs, the column value is the GTID of the transaction being executed by the worker when the error occurred.
The error number and error message of the most recent
error that caused the worker thread to stop. An error
number of 0 and message of the empty string mean “no
error.” If the
LAST_ERROR_MESSAGE value is not empty,
the error values also appear in the slave's error log.
All error codes and messages displayed in the
LAST_ERROR_MESSAGE columns correspond
to error values listed in
Section C.3, “Server Error Codes and Messages”.
A timestamp in
YYMMDD HH:MM:SS format
that shows when the most recent worker error occurred.