?在數據庫日常維護中,開發人員是最讓人頭痛的,很多時候都會由于SQL語句寫的有問題導致服務器出問題,導致資源耗盡。最危險的操作就是在做DML操作的時候忘加where條件,導致全表更新,這是作為運維或者DBA的我們改如何處理呢?下面我分別針對update和delete操作忘加where條件導致全表更新的處理方法。
一. update 忘加where條件誤操作恢復數據(binglog格式必須是ROW)
1.創建測試用的數據表
mysql> create table t1 (-> id int unsigned not null auto_increment,-> name char(20) not null,-> sex enum('f','m') not null default 'm',-> address varchar(30) not null,-> primary key(id)-> );
Query OK, 0 rows affected (0.31 sec)mysql>
2.插入測試數據
mysql> insert into t1 (name,sex,address)values('daiiy','m','guangzhou');
Query OK, 1 row affected (0.01 sec)mysql> insert into t1 (name,sex,address)values('tom','f','shanghai');
Query OK, 1 row affected (0.00 sec)mysql> insert into t1 (name,sex,address)values('liany','m','beijing');
Query OK, 1 row affected (0.00 sec)mysql> insert into t1 (name,sex,address)values('lilu','m','zhuhai');
Query OK, 1 row affected (0.05 sec)mysql>
3.現在需要將id等于2的用戶的地址改為zhuhai,update時沒有添加where條件
mysql> select * from t1;
+----+-------+-----+-----------+
| id | name | sex | address |
+----+-------+-----+-----------+
| 1 | daiiy | m | guangzhou |
| 2 | tom | f | shanghai |
| 3 | liany | m | beijing |
| 4 | lilu | m | zhuhai |
+----+-------+-----+-----------+
4 rows in set (0.01 sec)mysql> update t1 set address='zhuhai';
Query OK, 3 rows affected (0.09 sec)
Rows matched: 4 Changed: 3 Warnings: 0mysql> select * from t1;
+----+-------+-----+---------+
| id | name | sex | address |
+----+-------+-----+---------+
| 1 | daiiy | m | zhuhai |
| 2 | tom | f | zhuhai |
| 3 | liany | m | zhuhai |
| 4 | lilu | m | zhuhai |
+----+-------+-----+---------+
4 rows in set (0.00 sec)mysql>
4.開始恢復,在線上的話,應該比較復雜,要先進行鎖表,以免數據再次被污染。(鎖表,查看正在寫哪個二進制日志)
mysql> lock tables t1 read ;
Query OK, 0 rows affected (0.00 sec)mysql> show master status;
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000024 | 1852 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)mysql>
5.分析二進制日志,并且在其中找到相關記錄,在更新時是address='zhuhai',我們可以在日志中過濾出來。
[root@localhost mysql]# mysqlbinlog --no-defaults -v -v --base64-output=DECODE-ROWS mysql-bin.000024 | grep -B 15 'zhuhai'
# at 1629
# at 1679
#140305 10:52:24 server id 1 end_log_pos 1679 Table_map: `db01`.`t1` mapped to number 38
#140305 10:52:24 server id 1 end_log_pos 1825 Update_rows: table id 38 flags: STMT_END_F
### UPDATE db01.t1
### WHERE
### @1=1 /* INT meta=0 nullable=0 is_null=0 */
### @2='daiiy' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='guangzhou' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### SET
### @1=1 /* INT meta=0 nullable=0 is_null=0 */
### @2='daiiy' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='zhuhai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### UPDATE db01.t1
### WHERE
### @1=2 /* INT meta=0 nullable=0 is_null=0 */
### @2='tom' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=1 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='shanghai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### SET
### @1=2 /* INT meta=0 nullable=0 is_null=0 */
### @2='tom' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=1 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='zhuhai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### UPDATE db01.t1
### WHERE
### @1=3 /* INT meta=0 nullable=0 is_null=0 */
### @2='liany' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='beijing' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### SET
### @1=3 /* INT meta=0 nullable=0 is_null=0 */
### @2='liany' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='zhuhai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
可以看見里面記錄了每一行的變化,這也是binglog格式要一定是row才行的原因。其中@1,@2,@3,@4,分別對應表中id,name,sex,address字段。相信大家看到這里有點明白了吧,對,沒錯,你猜到了,我們將相關記錄轉換為sql語句,重新導入數據庫。
6.處理分析處理的二進制日志
[root@localhost mysql]# mysqlbinlog --no-defaults -v -v --base64-output=DECODE-ROWS mysql-bin.000024 | sed -n '/# at 1679/,/COMMIT/p' > t1.txt
[root@localhost mysql]# cat t1.txt
# at 1679
#140305 10:52:24 server id 1 end_log_pos 1679 Table_map: `db01`.`t1` mapped to number 38
#140305 10:52:24 server id 1 end_log_pos 1825 Update_rows: table id 38 flags: STMT_END_F
### UPDATE db01.t1
### WHERE
### @1=1 /* INT meta=0 nullable=0 is_null=0 */
### @2='daiiy' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='guangzhou' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### SET
### @1=1 /* INT meta=0 nullable=0 is_null=0 */
### @2='daiiy' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='zhuhai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### UPDATE db01.t1
### WHERE
### @1=2 /* INT meta=0 nullable=0 is_null=0 */
### @2='tom' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=1 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='shanghai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### SET
### @1=2 /* INT meta=0 nullable=0 is_null=0 */
### @2='tom' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=1 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='zhuhai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### UPDATE db01.t1
### WHERE
### @1=3 /* INT meta=0 nullable=0 is_null=0 */
### @2='liany' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='beijing' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### SET
### @1=3 /* INT meta=0 nullable=0 is_null=0 */
### @2='liany' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='zhuhai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
# at 1825
#140305 10:52:24 server id 1 end_log_pos 1852 Xid = 26
COMMIT/*!*/;
[root@localhost mysql]#
[root@localhost mysql]# sed '/WHERE/{:a;N;/SET/!ba;s/\([^\n]*\)\n\(.*\)\n\(.*\)/\3\n\2\n\1/}' t1.txt | sed -r '/WHERE/{:a;N;/@4/!ba;s/### @2.*//g}' | sed 's/### //g;s/\/\*.*/,/g' | sed '/WHERE/{:a;N;/@1/!ba;s/,/;/g};s/#.*//g;s/COMMIT,//g' | sed '/^$/d' > recover.sql
功能:將where 和set位置對調
命令剖析:
/WHERE/ #包含WHERE:a; #創建一個labela;
N; #追加下一個輸入行到讀取行的末尾,讀入到模式空間
/SET/!ba; # 如果不是/SET/,返回a,也就是重復讀,一直讀到/SET/之前(buffer的內容是WHERE\n.......\nSET)第1步: s #替換命令,例如s/a/b 將a替換為b第2步:\([^\n]*\)\n\(.*\)\n\(.*\) \ #轉義字符[^\n]* == buffer中的where(.*\) #單符號(.)匹配除換行符以外的單個字符,*同上;[^\n]*\ #代表非換行符(回車)開頭,*表示匹配零或多個字符\n #換行第3步\3\n\2\n\1 \3 == 內存中的set,第三個括號中的內容\2 == 內存中原來where與set之間的內容,第二個括號中的內容\1 == 內存中的where,第一個括號中的內容功能:這句做了兩個事情1.把字符串### 替換成 空格 2.把/*往后的內容 替換成, s/### //g #將### 替換成空串,\ #轉義字符\/\*.* #匹配/*之后出換行符外所有內容功能:這句把字符串包含@7的行中的全部(,)換成空格/@7/ #匹配包含@7的行s/,// #將,替換為空串g #全部替換
[root@localhost mysql]# cat recover.sql
UPDATE db01.t1
SET@1=1 ,@2='daiiy' ,@3=2 ,@4='guangzhou' ,
WHERE@1=1 ;
UPDATE db01.t1
SET@1=2 ,@2='tom' ,@3=1 ,@4='shanghai' ,
WHERE@1=2 ;
UPDATE db01.t1
SET@1=3 ,@2='liany' ,@3=2 ,@4='beijing' ,
WHERE@1=3 ;
[root@localhost mysql]#
將文件中的@1,@2,@3,@4替換為t1表中id,name,sex,address字段,并刪除最后字段的","號
[root@localhost mysql]# sed -i 's/@1/id/g;s/@2/name/g;s/@3/sex/g;s/@4/address/g' recover.sql
[root@localhost mysql]# sed -i -r 's/(address=.*),/\1/g' recover.sql
[root@localhost mysql]# cat recover.sql
UPDATE db01.t1
SETid=1 ,name='daiiy' ,sex=2 ,address='guangzhou'
WHEREid=1 ;
UPDATE db01.t1
SETid=2 ,name='tom' ,sex=1 ,address='shanghai'
WHEREid=2 ;
UPDATE db01.t1
SETid=3 ,name='liany' ,sex=2 ,address='beijing'
WHEREid=3 ;
[root@localhost mysql]#
7.到這里日志就處理好了,現在導入即可(導入數據后,解鎖表);
mysql> source recover.sql;
Query OK, 1 row affected (0.12 sec)
Rows matched: 1 Changed: 1 Warnings: 0Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0mysql> select * from t1;
+----+-------+-----+-----------+
| id | name | sex | address |
+----+-------+-----+-----------+
| 1 | daiiy | m | guangzhou |
| 2 | tom | f | shanghai |
| 3 | liany | m | beijing |
| 4 | lilu | m | zhuhai |
+----+-------+-----+-----------+
4 rows in set (0.00 sec)mysql>
可以看見數據已經完全恢復,這種方法的優點是快速,方便。
二. delete 忘加where條件誤刪除恢復(binglog格式必須是ROW)
其實這和update忘加條件差不多,不過這處理更簡單,這里就用上面那張表做測試吧
1.模擬誤刪除數據
mysql> select * from t1;
+----+-------+-----+-----------+
| id | name | sex | address |
+----+-------+-----+-----------+
| 1 | daiiy | m | guangzhou |
| 2 | tom | f | shanghai |
| 3 | liany | m | beijing |
| 4 | lilu | m | zhuhai |
+----+-------+-----+-----------+
4 rows in set (0.00 sec)mysql> delete from t1;
Query OK, 4 rows affected (0.03 sec)mysql> select * from t1;
Empty set (0.00 sec)mysql>
2.在binglog中去查找相關記錄
[root@localhost mysql]# mysqlbinlog --no-defaults --base64-output=decode-rows -v -v mysql-bin.000024 | sed -n '/### DELETE FROM db01.t1/,/COMMIT/p' > delete.txt
[root@localhost mysql]# cat delete.txt
### DELETE FROM db01.t1
### WHERE
### @1=1 /* INT meta=0 nullable=0 is_null=0 */
### @2='daiiy' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='guangzhou' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### DELETE FROM db01.t1
### WHERE
### @1=2 /* INT meta=0 nullable=0 is_null=0 */
### @2='tom' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=1 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='shanghai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### DELETE FROM db01.t1
### WHERE
### @1=3 /* INT meta=0 nullable=0 is_null=0 */
### @2='liany' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='beijing' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
### DELETE FROM db01.t1
### WHERE
### @1=4 /* INT meta=0 nullable=0 is_null=0 */
### @2='lilu' /* STRING(60) meta=65084 nullable=0 is_null=0 */
### @3=2 /* ENUM(1 byte) meta=63233 nullable=0 is_null=0 */
### @4='zhuhai' /* VARSTRING(90) meta=90 nullable=0 is_null=0 */
# at 2719
#140305 11:41:00 server id 1 end_log_pos 2746 Xid = 78
COMMIT/*!*/;
[root@localhost mysql]#
3.將記錄轉換為SQL語句
[root@localhost mysql]# cat delete.txt | sed -n '/###/p' | sed 's/### //g;s/\/\*.*/,/g;s/DELETE FROM/INSERT INTO/g;s/WHERE/SELECT/g;' | sed -r 's/(@4.*),/\1;/g' | sed 's/@[1-9]=//g' > t1.sql
[root@localhost mysql]# cat t1.sql
INSERT INTO db01.t1
SELECT1 ,'daiiy' ,2 ,'guangzhou' ;
INSERT INTO db01.t1
SELECT2 ,'tom' ,1 ,'shanghai' ;
INSERT INTO db01.t1
SELECT3 ,'liany' ,2 ,'beijing' ;
INSERT INTO db01.t1
SELECT4 ,'lilu' ,2 ,'zhuhai' ;
[root@localhost mysql]#
4.導入數據,驗證數據完整性
mysql> source t1.sql;
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0Query OK, 1 row affected (0.02 sec)
Records: 1 Duplicates: 0 Warnings: 0Query OK, 1 row affected (0.02 sec)
Records: 1 Duplicates: 0 Warnings: 0Query OK, 1 row affected (0.01 sec)
Records: 1 Duplicates: 0 Warnings: 0mysql> select * from t1;
ERROR 1046 (3D000): No database selected
mysql> select * from db01.t1;
+----+-------+-----+-----------+
| id | name | sex | address |
+----+-------+-----+-----------+
| 1 | daiiy | m | guangzhou |
| 2 | tom | f | shanghai |
| 3 | liany | m | beijing |
| 4 | lilu | m | zhuhai |
+----+-------+-----+-----------+
4 rows in set (0.00 sec)mysql>
到這里數據就完整回來了。將binglog格式設置為row有利有弊,好處是記錄了每一行的實際變化,在主從復制時也不容易出問題。但是由于記錄每行的變化,會占用大量磁盤,主從復制時帶寬占用會有所消耗。到底是使用row還是mixed,需要在實際工作中自己去衡量,但從整體上來說,binglog的格式設置為row,都是不二的選擇。
總結:
所以在數據庫操作的過程中我們需要格外小心,當然開發那邊我們需要做好權限的控制,不過有一個參數可以解決我們的問題,讓我們不用擔心類似的問題發生:
在[mysql]段落開啟這個參數:
safe-updates
這樣當我們在做DML操作時忘記加where條件時,mysqld服務器是不會執行操作的:
mysql> select * from t1;
+----+------------------+
| id | name |
+----+------------------+
| 1 | yayun |
| 2 | atlas |
| 3 | mysql |
| 6 | good yayun heheh |
+----+------------------+
4 rows in set (0.00 sec)mysql> delete from t1;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
mysql>
https://blog.csdn.net/weixin_33674976/article/details/92863378?