**********************mysqldump 所需權限*************************************

dump tables:SELECT

dump views:SHOW VIEW

dump triggers:TRIGGER

LOCK TABLES（如果不使用--single-transaction）

RELOAD,SUPER, REPLICATION CLIENT (--master-data=2)

數據庫字符集更改：ALTER DATABASE

**********************mysqldump 適用場景************************************

全量表結構、存儲過程、觸發器等備份

單表（小表）備份

**********************mysqldump 缺點****************************************

邏輯備份，導出比較慢

單線程備份，5.7有mysqlpump以及開源版的mydumper可進行并行和壓縮備份恢復

使用--single-transaction可實現在線備份，但是碰到操作時間過長的事物可能會使數據庫出問題

5.6以下版本使用可能會使buffer pool熱數據刷出，5.6及以上版本可通過innodb_old_blocks_time來控制熱數據的進出

**********************mysqldump 常用語句****************************************

只導出表結構：

mysqldump -d --trigger=false

只導出存儲過程：

mysqldump -f -Rtdn --trigger=false

只導出觸發器：

mysqldump -f -tdn --trigger

只導出事件：

mysqldump -f -Etdn --triggers=False

只導出數據:

mysqldump -f --single-transaction --triggers=false -t

導出表中某些行：

mysqldump dbname --where="1=1 limit 1000"

在線建從庫：

mysqldump --master-data=2 --single-transaction -A

**********************mysqldump 后臺工作細節**************************************

查看general log是否打開：

mysql> set global general_log = on;?

Query OK, 0 rows affected (0.01 sec)

mysql> show variables like '%general%';

+------------------+-----------------------------------------------------+

| Variable_name ? ?| Value ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |

+------------------+-----------------------------------------------------+

| general_log ? ? ?| ON ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|

| general_log_file | /app/data/mysql/3336/data/BJ-ECS-XHM-TEST-YL-19.log |

+------------------+-----------------------------------------------------+

2 rows in set (0.02 sec)

創建數據庫及測試數據：

create database gaoquan;

create table t1(id int not null primary key auto_increment,name varchar(10) not null,age int not null);

insert into t1(name,age) values('name1',10),('name2',10),('name3',10),('name4',10),('name5',10),('name6',10),('name7',10),('name8',10),('name9',10);

create table t2(id int not null primary key auto_increment,name varchar(10) not null,age int not null);

insert into t2(name,age) values('name1',10),('name2',10),('name3',10),('name4',10),('name5',10),('name6',10),('name7',10),('name8',10),('name9',10);

創建mysqldump備份用戶：

grant select,show view,trigger,lock tables on *.* to backup@'%' identified by 'backup007';

不開啟--single-transaction執行備份：

/usr/local/mysql/bin/mysqldump -u backup -p gaoquan -h 10.50.12.33 -P 3336 ?

general log 輸出：

160105 11:29:55 ?296 Connectbackup@10.50.12.33 on?

?296 Query/*!40100 SET @@SQL_MODE='' */

?296 Query/*!40103 SET TIME_ZONE='+00:00' */

?296 QuerySHOW VARIABLES LIKE 'gtid\_mode'

?296 QuerySELECT LOGFILE_GROUP_NAME, FILE_NAME, TOTAL_EXTENTS, INITIAL_SIZE, ENGINE, EXTRA FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'UNDO LOG' AND FILE_NAME IS NOT NULL AND LOGFILE_GROUP_NAME IN (SELECT DISTINCT LOGFILE_GROUP_NAME FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'DATAFILE' AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA IN ('gaoquan'))) GROUP BY LOGFILE_GROUP_NAME, FILE_NAME, ENGINE ORDER BY LOGFILE_GROUP_NAME

?296 QuerySELECT DISTINCT TABLESPACE_NAME, FILE_NAME, LOGFILE_GROUP_NAME, EXTENT_SIZE, INITIAL_SIZE, ENGINE FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'DATAFILE' AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA IN ('gaoquan')) ORDER BY TABLESPACE_NAME, LOGFILE_GROUP_NAME

?296 QuerySHOW VARIABLES LIKE 'ndbinfo\_version'

?296 Init DBgaoquan

?296 Queryshow tables

?296 QueryLOCK TABLES `t1` READ /*!32311 LOCAL */,`t2` READ /*!32311 LOCAL */

?296 Queryshow table status like 't1'

?296 QuerySET SQL_QUOTE_SHOW_CREATE=1

?296 QuerySET SESSION character_set_results = 'binary'

?296 Queryshow create table `t1`

?296 QuerySET SESSION character_set_results = 'utf8'

?296 Queryshow fields from `t1`

?296 QuerySELECT /*!40001 SQL_NO_CACHE */ * FROM `t1`

?296 QuerySET SESSION character_set_results = 'binary'

?296 Queryuse `gaoquan`

?296 Queryselect @@collation_database

?296 QuerySHOW TRIGGERS LIKE 't1'

?296 QuerySET SESSION character_set_results = 'utf8'

?296 Queryshow table status like 't2'

?296 QuerySET SQL_QUOTE_SHOW_CREATE=1

?296 QuerySET SESSION character_set_results = 'binary'

?296 Queryshow create table `t2`

?296 QuerySET SESSION character_set_results = 'utf8'

?296 Queryshow fields from `t2`

?296 QuerySELECT /*!40001 SQL_NO_CACHE */ * FROM `t2`

?296 QuerySET SESSION character_set_results = 'binary'

?296 Queryuse `gaoquan`

?296 Queryselect @@collation_database

?296 QuerySHOW TRIGGERS LIKE 't2'

?296 QuerySET SESSION character_set_results = 'utf8'

?296 QueryUNLOCK TABLES

?296 Quit

原理：

加全局讀鎖(防止備份數據不一致)->當前字符集會做一些處理，防止亂碼->獲取建表信息生成建表語句->獲取行記錄從而轉換成insert插入語句->釋放讀鎖

開啟--single-transaction備份：

/usr/local/mysql/bin/mysqldump -u backup -p gaoquan -h 10.50.12.33 -P 3336 ?--single-transaction

160105 11:33:41 ?298 Connectbackup@10.50.12.33 on?

?298 Query/*!40100 SET @@SQL_MODE='' */

?298 Query/*!40103 SET TIME_ZONE='+00:00' */

?298 QuerySET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ

?298 QuerySTART TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */

?298 QuerySHOW VARIABLES LIKE 'gtid\_mode'

?298 QueryUNLOCK TABLES

?298 QuerySELECT LOGFILE_GROUP_NAME, FILE_NAME, TOTAL_EXTENTS, INITIAL_SIZE, ENGINE, EXTRA FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'UNDO LOG' AND FILE_NAME IS NOT NULL AND LOGFILE_GROUP_NAME IN (SELECT DISTINCT LOGFILE_GROUP_NAME FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'DATAFILE' AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA IN ('gaoquan'))) GROUP BY LOGFILE_GROUP_NAME, FILE_NAME, ENGINE ORDER BY LOGFILE_GROUP_NAME

?298 QuerySELECT DISTINCT TABLESPACE_NAME, FILE_NAME, LOGFILE_GROUP_NAME, EXTENT_SIZE, INITIAL_SIZE, ENGINE FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'DATAFILE' AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA IN ('gaoquan')) ORDER BY TABLESPACE_NAME, LOGFILE_GROUP_NAME

?298 QuerySHOW VARIABLES LIKE 'ndbinfo\_version'

?298 Init DBgaoquan

?298 QuerySAVEPOINT sp

?298 Queryshow tables

?298 Queryshow table status like 't1'

?298 QuerySET SQL_QUOTE_SHOW_CREATE=1

?298 QuerySET SESSION character_set_results = 'binary'

?298 Queryshow create table `t1`

?298 QuerySET SESSION character_set_results = 'utf8'

?298 Queryshow fields from `t1`

?298 QuerySELECT /*!40001 SQL_NO_CACHE */ * FROM `t1`

?298 QuerySET SESSION character_set_results = 'binary'

?298 Queryuse `gaoquan`

?298 Queryselect @@collation_database

?298 QuerySHOW TRIGGERS LIKE 't1'

?298 QuerySET SESSION character_set_results = 'utf8'

?298 QueryROLLBACK TO SAVEPOINT sp

?298 Queryshow table status like 't2'

?298 QuerySET SQL_QUOTE_SHOW_CREATE=1

?298 QuerySET SESSION character_set_results = 'binary'

?298 Queryshow create table `t2`

?298 QuerySET SESSION character_set_results = 'utf8'

?298 Queryshow fields from `t2`

?298 QuerySELECT /*!40001 SQL_NO_CACHE */ * FROM `t2`

?298 QuerySET SESSION character_set_results = 'binary'

?298 Queryuse `gaoquan`

?298 Queryselect @@collation_database

?298 QuerySHOW TRIGGERS LIKE 't2'

?298 QuerySET SESSION character_set_results = 'utf8'

?298 QueryROLLBACK TO SAVEPOINT sp

?298 QueryRELEASE SAVEPOINT sp

?298 Quit

原理：

更改當前會話隔離級別為rr->開始事物->釋放表鎖->導出建表語句->設置一個savepoint->導出表數據->回滾到savepoint sp->對其他表重復該過程->最后釋放savepoint

整個過程，沒有任何鎖。RR隔離級別保證在事務中只讀取本事務之前的一致性的數據 。 rollback to savepoint sp; 保證了對數據庫中的數據沒有影響。?

轉載于:https://blog.51cto.com/gaoquan/1731721

總結

以上是生活随笔為你收集整理的mysqldump原理及实验的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。