新特性解讀 | MySQL 8.0 錯誤日誌加強特性

做者：楊濤濤

MySQL 8.0 從新定義了錯誤日誌輸出和過濾，改善了原來臃腫而且可讀性不好的錯誤日誌。

好比增長了 JSON 輸出，在原來的日誌後面以序號以及 JSON 後綴的方式展現

好比我機器上的 MySQL 以 JSON 保存的錯誤日誌 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 輸出錯誤日誌後可讀性和可操做性加強了許多。這裏能夠用 Linux 命令 jq 或者把這個字串 COPY 到其餘解析 JSON 的工具方便處理。

只想很是快速的拿出錯誤信息，忽略其餘信息。

[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';

完了在設置變量 SET GLOBAL log_error_services = 'log_filter_internal; log_sink_json';

格式爲：過濾規則；日誌輸出；[過濾規則]日誌輸出；

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)

如今設置 JSON 輸出，輸出到系統日誌的同時輸出到 JSON 格式日誌。

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。我以前已經把表 a 物理文件刪掉了。

mysql> select * from a;
ERROR 1812 (HY000): Tablespace is missing for table `ytt2`.`a`.

如今錯誤日誌裏有 5 條記錄。

[root@centos-ytt80 mysql80]# tailf  mysqld.log

2019-09-03T08:16:12.111808Z 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: 71
2019-09-03T08:16:12.112227Z 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 日誌裏也有 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，過濾的規則我看仍是沒變。

那咱們如今給第二條日誌輸出加過濾規則

先把過濾日誌的部件安裝起來

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，其他的一概過濾掉。

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`.

查看錯誤日誌和 JSON 錯誤日誌

發現錯誤日誌裏有一條 Warning，JSON 錯誤日誌裏的被過濾掉了。

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 秒只容許記錄一個 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)

屢次執行

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`.

如今錯誤日誌裏有三條 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，我這裏簡單介紹了下 MySQL 8.0 的錯誤日誌過濾以及 JSON 輸出。MySQL 8.0 的 component_log_filter_dragnet 部件過濾規則很是靈活，能夠參考手冊，根據它提供的語法寫出本身的過濾掉的日誌輸出。