The Slow Query Log If the slow query log is enabled and  FILE  is selected as an output destination, each statement written to the log is preceded by a line that begins with a  #  character and has these fields (with all fields on a single line): The statement execution time in seconds. The time to acquire locks in seconds. The number of rows sent to the client. The number of rows examined by the server layer (not counting any processing internal to storage engines). Enabling the  log_slow_extra  system variable (available as of MySQL 8.0.14) causes the server to write the following extra fields to  FILE  output in addition to those just listed ( TABLE  output is unaffected). Some field descriptions refer to status variable names. Consult the status variable descriptions for more information. However, in the slow query log, the counters are per-statement values, not cumulative per- session values. The statement thread identifier. The statement error number, or 0 if no error occurred. If the statement was terminated, the error number indicating why, or 0 if the statement terminated normally. The  Bytes_received  value for the statement. The  Bytes_sent  value for the statement. The  Handler_read_first  value for the statement. The  Handler_read_last  value for the statement. The  Handler_read_key  value for the statement. 1065 • Read_key:  N • Read_last:  N • Read_first:  N • Bytes_sent:  N • Bytes_received:  N • Killed:  N • Errno:  error_number • Thread_id:  ID • Rows_examined: • Rows_sent:  N • Lock_time:  duration • Query_time:  duration