備庫掛了：slave io/sql thread error

• 0.關鍵點:

  1.show slave status\G; 檢視掛了的原因
  2.一般處理完後要tcp校驗一下
  3.如果是宕機或者例項重啟，在主庫執行start slave前要在備庫上看看有沒有回滾程序ps aux | grep magiclog ，如果有 magiclog 程序在執行說明在回滾。回滾過程中不能執行start slave，不然會報各種slave err

• 1.報錯:檔案中位點>檔案大小
  Got fatal error 1236 from master when reading data from binary log: 'Client requested master to start replication from position > file size; the first event 'mysql-bin.000020' at 307263712, the last event read from '/u01/my3308/log/mysql-bin.000020' at 4, the last byte read from '/u01/my3308/log/mysql-bin.000020' at 4.'

  解決:重指位點 //MASTER_LOG_FILE為當前備份Relay_Master_Log_File的下一個,MASTER_LOG_POS=4
  stop slave ;
  CHANGE MASTER TO MASTER_LOG_FILE=’mysql-bin.016729’, MASTER_LOG_POS=4;
  start slave;
  select sleep(0.1);
  show slave status\G;

• 2.沒有報錯資訊，只是顯示 Slave_IO_Running: No Slave_SQL_Running: No

  用start slave；啟動時報錯如下
  1.Could not initialize master info structure; more error messages can be found in the MySQL error log
  看/u02/my3308/log/alert.log日誌,發現錯誤如下
  [ERROR] Error looking for file after /u01/my3308/log/relaylog.000064.
  仔細看位點會發現很奇怪的事情
  Read_Master_Log_Pos: 95926035
  Exec_Master_Log_Pos: 95969857
  執行位點比讀master的位點還大了

  解決：沒辦法，只能reset然後重指位點了 記錄好Relay_Master_Log_File: 和 Exec_Master_Log_Pos:
  reset slave;
  CHANGE MASTER TO MASTER_LOG_FILE=’mysql-bin.001458’, MASTER_LOG_POS=266387470;
  start slave;
  select sleep(0.1);
  show slave status\G;

• 3.Slave failed to initialize relay log info structure from the repository
  解決:同樣的處理方法

• 4.如下錯誤
  Worker 15 failed executing transaction '' at master log mysql-bin.000012, end_log_pos 468767971; Could not execute Write_rows_v1 event on table cbu_nebulabody_00.short_url_0011; Duplicate entry '5730576' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log FIRST, end_log_pos 468767971
或者
Last_SQL_Errno: 1032
Could not execute Update_rows event on table cbu_vaseq7.vas_eq_enquiries_0102; Can't find record in 'vas_eq_enquiries_0102', Error_code: 1032; handler error HA_ERR_KEY_NOT_FOUND; the event's master log
mysql-bin.000417, end_log_pos 44444276, Error_code: 1032
或者
Cannot execute the current event group in the parallel mode. Encountered event Xid, relay-log name /u01/my3318/log/relaylog.000030, position 372 which prevents execution of this event group in parallel mode. Reason: the event is a part of a group that is unsupported in the parallel execution mode.

解決：直接跳過:sql_slave_skip_counter=1是指跳過一個事務的意思
stop slave;set global sql_slave_skip_counter=1;start slave;select sleep(0.1);show slave status\G;

• 5.其他報錯，可以選擇跳過錯誤
  show slave status\G;
  show variables like ‘%slave_parallel_workers’;
  set global slave_parallel_workers = 0;
  set global slave_exec_mode = smart;
  start slave;
  select sleep(0.1);
  show slave status\G;
  stop slave;
  set global slave_exec_mode = strict;
  set global slave_parallel_workers = 16;
  start slave;
  select sleep(0.1);
  show slave status\G;

• 6.GTID報錯