25.11.11.6 The replication_applier_status_by_worker Table

If the slave is not multi-threaded, this table shows the status of the applier thread. 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 replication_applier_status_by_coordinator table shows the status of the coordinator thread. This table provides details about the transactions applied, where the start timestamp refers to when the worker started applying the first event, and the end timestamp refers to when the last event of the transaction was applied.

The replication_applier_status_by_worker table has these columns:

• CHANNEL_NAME

  The replication channel which this row is displaying. There is always a default replication channel, and more replication channels can be added. See Section 17.2.3, “Replication Channels” for more information.

• WORKER_ID

  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.

• THREAD_ID

  The worker thread ID.

• SERVICE_STATE

  ON (thread exists and is active or idle) or OFF (thread no longer exists).

• LAST_ERROR_NUMBER, LAST_ERROR_MESSAGE

  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.

  Issuing RESET MASTER or RESET SLAVE resets the values shown in these columns.

  All error codes and messages displayed in the LAST_ERROR_NUMBER and LAST_ERROR_MESSAGE columns correspond to error values listed in Section B.3, “Server Error Codes and Messages”.

• LAST_ERROR_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when the most recent worker error occurred.

• LAST_APPLIED_TRANSACTION

  The global transaction ID (GTID) of the last transaction applied by this worker.

• LAST_APPLIED_TRANSACTION_ORIGINAL_COMMIT_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when the last transaction applied by this worker was committed on the original master.

• LAST_APPLIED_TRANSACTION_IMMEDIATE_COMMIT_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when the last transaction applied by this worker was committed on the immediate master.

• LAST_APPLIED_TRANSACTION_START_APPLY_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when this worker started applying the last applied transaction.

• LAST_APPLIED_TRANSACTION_END_APPLY_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when this worker finished applying the last applied transaction.

• APPLYING_TRANSACTION

  The global transaction ID (GTID) of the transaction this worker is currently applying.

• APPLYING_TRANSACTION_ORIGINAL_COMMIT_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when the transaction this worker is currently applying was committed on the original master.

• APPLYING_TRANSACTION_IMMEDIATE_COMMIT_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when the transaction this worker is currently applying was committed on the immediate master.

• APPLYING_TRANSACTION_START_APPLY_TIMESTAMP

  A timestamp in 'YYYY-MM-DD HH:MM:SS[.fraction]' format that shows when this worker started applying the transaction that is currently being applied.

When the Performance Schema is disabled, local timing information is not collected, so the fields showing the start and end timestamps for applied transactions are zero.

The replication_applier_status_by_worker table has these indexes:

• Primary key on (CHANNEL_NAME, WORKER_ID)

• Index on (THREAD_ID)

The following table shows the correspondence between replication_applier_status_by_worker columns and SHOW SLAVE STATUS columns.

replication_applier_status_by_worker Column	SHOW SLAVE STATUS Column
WORKER_ID	None
THREAD_ID	None
SERVICE_STATE	None
LAST_SEEN_TRANSACTION	None
LAST_ERROR_NUMBER	Last_SQL_Errno
LAST_ERROR_MESSAGE	Last_SQL_Error
LAST_ERROR_TIMESTAMP	Last_SQL_Error_Timestamp