mysqldump 一些参数体验

mysqldump -uroot -p'xxx'  -R --single-transaction --master-data=2 zjzc>$TODAY_DIR/zjzc/zjzc_${TODAY_DIR}.sql

mysqldump -uxxx -p --single-transaction --master-data=2 --routines --flush-logs --databases db1 db2 db3 > alldb.sql;

介绍下mysqldump一些备份参数:

  --routines, -R

           Include stored routines (procedures and functions) for the dumped databases in the output. Use of this
           option requires the SELECT privilege for the mysql.proc table. The output generated by using --routines
           contains CREATE PROCEDURE and CREATE FUNCTION statements to re-create the routines. However, these
           statements do not include attributes such as the routine creation and modification timestamps. This means
           that when the routines are reloaded, they will be created with the timestamps equal to the reload time.

           If you require routines to be re-created with their original timestamp attributes, do not use --routines.
           Instead, dump and reload the contents of the mysql.proc table directly, using a MySQL account that has
           appropriate privileges for the mysql database.

           Prior to MySQL 5.6.5, this option had no effect when used together with the --xml option. (Bug #11760384,
           Bug #52792)

包含存储程序(过程和函数) 对于转储的数据库到输出，使用这个选项需要SELECT 权限对于mysql.proc表,

通过使用--routines 生成包含 CREATE PROCEDURE and CREATE FUNCTION 语句来重新创建函数。

然而,那些语句不包含属性比如函数创建和修改时间戳。

这意味着 当函数被加载时, 它们会创建使用timestamps 等于加载时间

如果你需要程序被重新创建使用它们原来的timestamp 属性,不要使用--routines

 --flush-logs, -F

           Flush the MySQL server log files before starting the dump. This option requires the RELOAD privilege. If
           you use this option in combination with the --all-databases option, the logs are flushed for each
           database dumped. The exception is when using --lock-all-tables, --master-data, or --single-transaction:
           In this case, the logs are flushed only once, corresponding to the moment that all tables are locked. If
           you want your dump and the log flush to happen at exactly the same moment, you should use --flush-logs
           together with --lock-all-tables, --master-data, or --single-transaction.

Flush MySQL server log files 在开始dump前, 这个选项需要RELOAD 权限。

如果你使用这个选项 结合--all-databases option,  日志是刷新为每个数据库转储

例外是当使用 using --lock-all-tables, --master-data, or --single-transaction:

在这种情况下, logs只刷新一次,对应的时间点 所有的表被锁住

如果你需要你的dump和log flush 发生在同一个事件点,你需要使用--flush-logs
           together with --lock-all-tables, --master-data, or --single-transaction.

 --single-transaction

这个选项设置事务隔离级别为 REPEATABLE READ 发送一个START TRANSACTION SQL语句到服务器在开始dump数据前.

它只对于transactional tables  比如InnoDB是有用的

因为然后它备份数据库的一致性状态在START TRANSACTION被执行后 不会堵塞其他应用

当使用这个选项,你需要记录只有InnoDB 表是备份成一致性状态的

对于 MyISAM or MEMORY 表备份当使用这个选项时 仍旧会改变状态

当使用一个 --single-transaction 来处理,确保一个正确的dump文件(正确的表内容和binary log coordinates（坐标）)

没有其他的连接使用下面的语句: ALTER TABLE, CREATE
           TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE

一个一致性读是不能和那些语句分离的。

因此使用它们在一个表准备被dump 可能导致SELECT 被执行通过MYSQLDUMP 来检索表内存得到不正确的内容或者失败

--single-transaction 选项和e --lock-tables  选项是相互排斥的

因为LOCK TABLES 导致任何pending transactions被隐式的提交

   ·   --master-data[=value]

           Use this option to dump a master replication server to produce a dump file that can be used to set up
           another server as a slave of the master. It causes the dump output to include a CHANGE MASTER TO
           statement that indicates the binary log coordinates (file name and position) of the dumped server. These
           are the master server coordinates from which the slave should start replicating after you load the dump
           file into the slave.

           If the option value is 2, the CHANGE MASTER TO statement is written as an SQL comment, and thus is
           informative only; it has no effect when the dump file is reloaded. If the option value is 1, the
           statement is not written as a comment and takes effect when the dump file is reloaded. If no option value
           is specified, the default value is 1.

           This option requires the RELOAD privilege and the binary log must be enabled.

           The --master-data option automatically turns off --lock-tables. It also turns on --lock-all-tables,
           unless --single-transaction also is specified, in which case, a global read lock is acquired only for a
           short time at the beginning of the dump (see the description for --single-transaction). In all cases, any
           action on logs happens at the exact moment of the dump.

           It is also possible to set up a slave by dumping an existing slave of the master, using the --dump-slave
           option, which overrides --master-data and causes it to be ignored if both options are used.

           Prior to MySQL 5.6.4, this option was required for dumping the replication log tables (see
           Section 17.2.2, “Replication Relay and Status Logs”).

使用这个选项 来dump一个master 复制server 来产生一个dump 文件可以用于设置另外的server 作为master的一个slave.

它可以让dump 输出包含一个CHANGE MASTER TO 语句表明binary log coordinates (文件和位置)

这些是master server 的坐标 slave 应该开始复制在加载dump文件到slave后。

如果选项的值是2, CHANGE MASTER TO 语句是写成一个SQL注释,因此 只是提供信息的,

没有影响当dump 文件被加载时。 如果选项是1, 语句不是写成注释,当dump 文件被加载时是生效的

如果选项没有指定值,默认是1

这个选项需要RELOAD 权限和binary log 必须启用

 --master-data 选项会自动的关闭 --lock-tables. 它也开启--lock-all-tables,

除非你指定 --single-transaction  在这种情况下,一个 global read lock是需要的在dumo开始的短暂时间内

它也可以用于设置一个slave 通过dump 一个存在的master的slave,使用 --dump-slave选项，