MySQL 8.0 重新定義了錯誤日志輸出和過濾，改善了原來臃腫并且可讀性很差的錯誤日志。比如增加了 json 輸出，在原來的日志后面以序號以及 JSON 后綴的方式展示。比如我機器上的 MySQL 以 JSON 保存的錯誤日志 mysqld.log.00.json：[root@centos-ytt80 mysql80]# jq . mysqld.log.00.json{ "log_type": 1, "prio": 1, "err_code": 12592, "subsystem": "InnoDB", "msg": "Operating system error number 2 in a file operation.", "time": "2019-09-03T08:16:12.111808Z", "thread": 8, "err_symbol": "ER_IB_MSG_767", "SQL_state": "HY000", "label": "Error"}{ "log_type": 1, "prio": 1, "err_code": 12593, "subsystem": "InnoDB", "msg": "The error means the system cannot find the path specified.", "time": "2019-09-03T08:16:12.111915Z", "thread": 8, "err_symbol": "ER_IB_MSG_768", "SQL_state": "HY000", "label": "Error"}{ "log_type": 1, "prio": 1, "err_code": 12216, "subsystem": "InnoDB", "msg": "Cannot open datafile for read-only: './ytt2/a.ibd' OS error: 71", "time": "2019-09-03T08:16:12.111933Z", "thread": 8, "err_symbol": "ER_IB_MSG_391", "SQL_state": "HY000", "label": "Error"}以 JSON 輸出錯誤日志后可讀性和可操作性增強了許多。這里可以用 Linux 命令 jq 或者把這個字串 COPY 到其他解析 JSON 的工具方便處理。只想非常快速的拿出錯誤信息，忽略其他信息。[root@centos-ytt80 mysql80]# jq '.msg' mysqld.log.00.json"Operating system error number 2 in a file operation.""The error means the system cannot find the path specified.""Cannot open datafile for read-only: './ytt2/a.ibd' OS error: 71""Cannot calculate statistics for table `ytt2`.`a` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.""Cannot calculate statistics for table `ytt2`.`a` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue."使用 JSON 輸出的前提是安裝 JSON 輸出部件。
INSTALL COMPONENT 'file://component_log_sink_json';完了在設(shè)置變量 SET GLOBAL log_error_services = 'log_filter_internal; log_sink_json';格式為：過濾規(guī)則；日志輸出；[過濾規(guī)則]日志輸出；查看安裝好的部件mysql> select * from mysql.component;+--------------+--------------------+---------------------------------------+| component_id | component_group_id | component_urn |+--------------+--------------------+---------------------------------------+| 2 | 1 | file://component_log_sink_json |+--------------+--------------------+---------------------------------------+3 rows in set (0.00 sec)現(xiàn)在設(shè)置 JSON 輸出，輸出到系統(tǒng)日志的同時輸出到 JSON 格式日志。mysql> SET persist log_error_services = 'log_filter_internal; log_sink_internal; log_sink_json';Query OK, 0 rows affected (0.00 sec)來測試一把。我之前已經(jīng)把表 a 物理文件刪掉了。mysql> select * from a;ERROR 1812 (HY000): Tablespace is missing for table `ytt2`.`a`.現(xiàn)在錯誤日志里有 5 條記錄。[root@centos-ytt80 mysql80]# tailf mysqld.log2019-09-03T08:16:12.111808Z 8 [ERROR] [MY-012592] [InnoDB] Operating system error number 2 in a file operation.2019-09-03T08:16:12.111915Z 8 [ERROR] [MY-012593] [InnoDB] The error means the system cannot find the path specified.2019-09-03T08:16:12.111933Z 8 [ERROR] [MY-012216] [InnoDB] Cannot open datafile for read-only: './ytt2/a.ibd' OS error: 712019-09-03T08:16:12.112227Z 8 [Warning] [MY-012049] [InnoDB] Cannot calculate statistics for table `ytt2`.`a` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.2019-09-03T08:16:14.902617Z 8 [Warning] [MY-012049] [InnoDB] Cannot calculate statistics for table `ytt2`.`a` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.JSON 日志里也有 5 條記錄。[root@centos-ytt80 mysql80]# tailf mysqld.log.00.json{ "log_type" : 1, "prio" : 1, "err_code" : 12592, "subsystem" : "InnoDB", "msg" : "Operating system error number 2 in a file operation.", "time" : "2019-09-03T08:16:12.111808Z", "thread" : 8, "err_symbol" : "ER_IB_MSG_767", "SQL_state" : "HY000", "label" : "Error" }{ "log_type" : 1, "prio" : 1, "err_code" : 12593, "subsystem" : "InnoDB", "msg" : "The error means the system cannot find the path specified.", "time" : "2019-09-03T08:16:12.111915Z", "thread" : 8, "err_symbol" : "ER_IB_MSG_768", "SQL_state" : "HY000", "label" : "Error" }{ "log_type" : 1, "prio" : 1, "err_code" : 12216, "subsystem" : "InnoDB", "msg" : "Cannot open datafile for read-only: './ytt2/a.ibd' OS error: 71", "time" : "2019-09-03T08:16:12.111933Z", "thread" : 8, "err_symbol" : "ER_IB_MSG_391", "SQL_state" : "HY000", "label" : "Error" }{ "log_type" : 1, "prio" : 2, "err_code" : 12049, "subsystem" : "InnoDB", "msg" : "Cannot calculate statistics for table `ytt2`.`a` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.", "time" : "2019-09-03T08:16:12.112227Z", "thread" : 8, "err_symbol" : "ER_IB_MSG_224", "SQL_state" : "HY000", "label" : "Warning" }{ "log_type" : 1, "prio" : 2, "err_code" : 12049, "subsystem" : "InnoDB", "msg" : "Cannot calculate statistics for table `ytt2`.`a` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.", "time" : "2019-09-03T08:16:14.902617Z", "thread" : 8, "err_symbol" : "ER_IB_MSG_224", "SQL_state" : "HY000", "label" : "Warning" }那可能有人就問了，這有啥意義呢？只是把格式變了，過濾的規(guī)則我看還是沒變。那我們現(xiàn)在給第二條日志輸出加過濾規(guī)則先把過濾日志的部件安裝起來INSTALL COMPONENT 'file://component_log_filter_dragnet';mysql> SET persist log_error_services = 'log_filter_internal; log_sink_internal; log_filter_dragnet;log_sink_json';Query OK, 0 rows affected (0.00 sec)只保留 error，其余的一律過濾掉。SET GLOBAL dragnet.log_error_filter_rules = 'IF prio>=WARNING THEN drop.';檢索一張誤刪的表mysql> select * from a;ERROR 1812 (HY000): Tablespace is missing for table `ytt2`.`a`.查看錯誤日志和 JSON 錯誤日志發(fā)現(xiàn)錯誤日志里有一條 Warning，JSON 錯誤日志里的被過濾掉了。2019-09-03T08:22:32.978728Z 8 [Warning] [MY-012049] [InnoDB] Cannot calculate statistics for table `ytt2`.`a` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.再舉個例子，每 60 秒只允許記錄一個 Warning 事件mysql> SET GLOBAL dragnet.log_error_filter_rules = 'IF prio==WARNING THEN throttle 1/60.';Query OK, 0 rows affected (0.00 sec)多次執(zhí)行mysql> select * from b;ERROR 1812 (HY000): Tablespace is missing for table `ytt2`.`b`.mysql> select * from b;ERROR 1812 (HY000): Tablespace is missing for table `ytt2`.`b`.mysql> select * from b;ERROR 1812 (HY000): Tablespace is missing for table `ytt2`.`b`.現(xiàn)在錯誤日志里有三條 warning 信息2019-09-03T08:49:06.820635Z 8 [Warning] [MY-012049] [InnoDB] Cannot calculate statistics for table `ytt2`.`b` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.2019-09-03T08:49:31.455907Z 8 [Warning] [MY-012049] [InnoDB] Cannot calculate statistics for table `ytt2`.`b` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.2019-09-03T08:50:00.430867Z 8 [Warning] [MY-012049] [InnoDB] Cannot calculate statistics for table `ytt2`.`b` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.mysqld.log.00.json 只有一條{ "log_type" : 1, "prio" : 2, "err_code" : 12049, "subsystem" : "InnoDB", "msg" : "Cannot calculate statistics for table `ytt2`.`b` because the .ibd file is missing. Please refer to http://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html for how to resolve the issue.", "time" : "2019-09-03T08:49:06.820635Z", "thread" : 8, "err_symbol" : "ER_IB_MSG_224", "SQL_state" : "HY000", "and_n_more" : 3, "label" : "Warning" }總結(jié)，我這里簡單介紹了下 MySQL 8.0 的錯誤日志過濾以及 JSON 輸出。MySQL 8.0 的component_log_filter_dragnet 部件過濾規(guī)則非常靈活，可以參考手冊，根據(jù)它提供的語法寫出自己的過濾掉的日志輸出。