Matt 隨筆

[MySQL] 使用 mysqldump備份 DB

用 mysqldump 做備份，如果要儘可能把完整的資料匯出，可以加上 --single-transaction，備份前 mysqldump 會先執行 BEGIN ，取得 READ LOCK 後，便能確定資料在執行 mysqldump 的過程中不會受到其它連線存取的干擾，也能 Dump 出較完整的資料。(使用此參數需有 READ LOCK 權限)

mysqldump --single-transaction --all-databases > all_db.sql

注意: 
1.表單較大時可以加上 --quick 
2.MySQL Cluster 不支援 --single-transaction

然而使用 --single-transaction 時最好搭配 --flush-logs 及 --master-data來維持 Binary Log 的完整性。(使用這二個參數皆需有 RELOAD 權限)

mysqldump --single-transaction --flush-logs --master-data --all-databases > all_db.sql

Binary Log 採用的是遞增備份，--flush-logs 便是把目前的 Binary Log 給 flush 出來 (若目前 MASTER_LOG_FILE 已經到 mysql-bin.000005，產生出來的檔案便是 mysql-bin.000006)，完成之後才進行 Dump 的作業。

而 --master-data (預設值為1) 則是在 Dump 出來的 SQL 語法中加入下面這一行，以記錄目前 Dump 的時間點。

CHANGE MASTER TO MASTER_LOG_FILE=mysql-bin.000006',MASTER_LOG_POS=4;

如果在未來執行匯入時 SQL 語法時， MySQL 便能很清楚的知道這次 Dump 出來的 SQL 在 Binary Log 中是屬於哪個位置。

註: 若不需理會 Binary Log 的位置時 (例如進行完整備份作業)，只要將 --master-data 設為 2 便會將 CHANGE MASTER 給註解起來純供參考用。

首先先 Kill 掉所有 MySQL 的連線

# on Linux
/etc/init.d/mysqld stop
# on FreeBSD
/usr/local/etc/rc.d/mysql-server stop
killall -9 mysqld
然後進入 MySQL 安全模式

mysqld_safe -u root --skip-grant-tables &
然後利用文字介面修改 MySQL root 密碼

mysql
>use mysql
>UPDATE user SET password=password(’這裡輸入你的密碼’) where user=’root’;
>FLUSH PRIVILEGES;
>exit

dump database

mysqladmin -uroot -p flush-logs
mysqldump phpbb2 -B -uroot -p –opt > phpbb2_20020601.sql
–databases 或 -B 日後會自動建立該資料庫

dump table

mysqldump phpbb2 -uroot -p –opt phpbb2_users > phpbb2_users_20020601.sql

DB backup
如果另外一台電腦上沒有phpbb2這個DB記得要新增一個

mysql -uroot -p -e “CREATE DATABASE phpbb2″

then

mysql phpbb2 -uroot -p < phpbb2_20020601.sql


A.5.4.1.1. Resetting the Root Password on Windows Systems

Use the following procedure for resetting the password for any MySQL root accounts on Windows:

Log on to your system as Administrator.

Stop the MySQL server if it is running. For a server that is running as a Windows service, go to the Services manager:

Start Menu -> Control Panel -> Administrative Tools -> Services
Then find the MySQL service in the list, and stop it.

If your server is not running as a service, you may need to use the Task Manager to force it to stop.

Create a text file and place the following statements in it. Replace the password with the password that you want to use.

UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
FLUSH PRIVILEGES;
The UPDATE and FLUSH statements each must be written on a single line. The UPDATE statement resets the password for all existing root accounts, and the FLUSH statement tells the server to reload the grant tables into memory.

Save the file. For this example, the file will be named C:\mysql-init.txt.

Open a console window to get to the command prompt:

Start Menu -> Run -> cmd
Start the MySQL server with the special --init-file option:

C:\> C:\mysql\bin\mysqld-nt --init-file=C:\mysql-init.txt
If you installed MySQL to a location other than C:\mysql, adjust the command accordingly.

The server executes the contents of the file named by the --init-file option at startup, changing each root account password.

You can also add the --console option to the command if you want server output to appear in the console window rather than in a log file.

Users of MySQL 4.1 and higher who installed MySQL using the MySQL Installation Wizard may need to specify a --defaults-file option:

C:\> "C:\Program Files\MySQL\MySQL Server 4.1\bin\mysqld-nt.exe"
--defaults-file="C:\Program Files\MySQL\MySQL Server 4.1\my.ini"
--init-file=C:\mysql-init.txt
The appropriate --defaults-file setting can be found using the Services Manager:

Start Menu -> Control Panel -> Administrative Tools -> Services
Find the MySQL service in the list, right-click on it, and choose the Properties option. The Path to executable field contains the --defaults-file setting.

After the server has started successfully, delete C:\mysql-init.txt.

Stop the MySQL server, then restart it in normal mode again. If you run the server as a service, start it from the Windows Services window. If you start the server manually, use whatever command you normally use.

You should now be able to connect to MySQL as root using the new password.