mydumper与myloader是一个优秀的第三方mysql数据库逻辑备份恢复工具，使用多线程的导出与导入。弥补了mysqldump单线程的不足。本文描述的是如何加快mydumper与myloader的导出与导入供大家参考。
有关mydumper与myloader其他事项可以参考：
mydumper安装及安装故障汇总
mydumper备份mysql数据库示例
myloader恢复mysql数据库示例
1、基于MyIsam引擎导出导入
a、表不分块导出及导入
[root@GZAPP tmp]# mydumper -u inno -p xxx -B bsom -T tb_access_log -o /backup/tmp/
[root@GZAPP tmp]# ls -hltr ###导出的数据文件为单个文件，大小在2.6GB
total 2.6G
-rw-r--r-- 1 root root 1.6K Jul 24 08:51 bsom.tb_access_log-schema.sql
-rw-r--r-- 1 root root 214 Jul 24 08:52 metadata
-rw-r--r-- 1 root root 2.6G Jul 24 08:52 bsom.tb_access_log.sql
###基于缺省线程数导入，且设定每个事务查询数为10000，此参数此时其实作用不大，因为表为myisam引擎
[root@GZAPP tmp]# myloader -u inno -p xxx -B tempdb -d /backup/tmp -v 3 -q 10000
[root@GZAPP tmp]# myloader -u inno -p xxx -B tempdb -d /backup/tmp -v 3 -q 10000
** Message: 4 threads created
** Message: Creating table `tempdb`.`tb_access_log`
** Message: Thread 4 shutting down
** Message: Thread 1 restoring `bsom`.`tb_access_log` part 0
** Message: Thread 3 shutting down
** Message: Thread 2 shutting down
root@localhost[tempdb]> show processlist;
+---------+---------+----------+--------+---------+--------+---------+------------------------------------------------+
| Id | User | Host | db | Command | Time | State | Info |
+---------+---------+----------+--------+---------+--------+---------+------------------------------------------------+
| 4452079 | root | localhost| tempdb | Query | 0 | init | show processlist |
| 4453793 | inno | localhost| tempdb | Sleep | 420 | | NULL |
| 4453794 | inno | localhost| tempdb | Query | 4 | update | INSERT INTO `tb_access_log` VALUES (506873,"325|
+---------+---------+----------+--------+---------+--------+---------+------------------------------------------------+
###从上面的线程数可以看出只有一个单线程在执行insert操作
b、表分块导出及导入
###下面的示例中使用500MB进行分块
[root@GZAPP tmp]# mydumper -u inno -p xxx -B bsom -T tb_access_log -F 500 -o /backup/tmp/
[root@GZAPP tmp]# ls -hltr
total 2.6G
-rw-r--r-- 1 root root 1.6K Jul 24 08:21 bsom.tb_access_log-schema.sql
-rw-r--r-- 1 root root 478M Jul 24 08:21 bsom.tb_access_log.00001.sql
-rw-r--r-- 1 root root 478M Jul 24 08:21 bsom.tb_access_log.00002.sql
-rw-r--r-- 1 root root 478M Jul 24 08:21 bsom.tb_access_log.00003.sql
-rw-r--r-- 1 root root 478M Jul 24 08:21 bsom.tb_access_log.00004.sql
-rw-r--r-- 1 root root 478M Jul 24 08:22 bsom.tb_access_log.00005.sql
-rw-r--r-- 1 root root 214 Jul 24 08:22 metadata
-rw-r--r-- 1 root root 241M Jul 24 08:22 bsom.tb_access_log.00006.sql
###由上可知，大表tb_access_log按接近500M被分割成了多个文件
[root@GZAPP tmp]# myloader -u inno -p xxx -B tempdb -t 6 -d /backup/tmp -v 3
** Message: 6 threads created
** Message: Creating database `tempdb`
** Message: Creating table `tempdb`.`tb_access_log`
** Message: Thread 1 restoring `bsom`.`tb_access_log` part 3
** Message: Thread 2 restoring `bsom`.`tb_access_log` part 5
** Message: Thread 5 restoring `bsom`.`tb_access_log` part 4
** Message: Thread 3 restoring `bsom`.`tb_access_log` part 6
** Message: Thread 4 restoring `bsom`.`tb_access_log` part 1
** Message: Thread 6 restoring `bsom`.`tb_access_log` part 2
#在下面的processlist可以看到，存在表级锁等待
+---------+-------+-----------+---------+---------+--------+-----------------------------+------------------------------------------------+
| Id | User | Host | db | Command | Time | State | Info |
+---------+-------+-----------+---------+---------+--------+-----------------------------+------------------------------------------------+
| 4452079 | root | localhost | bsom | Query | 0 | init | show processlist |
| 4452167 | inno | localhost | tempdb | Sleep | 769 | | NULL |
| 4452168 | inno | localhost | tempdb | Query | 36 | update | INSERT INTO `tb_access_log` VALUES (6367402,"0,|
| 4452169 | inno | localhost | tempdb | Query | 21 | Waiting for table level lock| INSERT INTO `tb_access_log` VALUES (12593865," |
| 4452170 | inno | localhost | tempdb | Query | 26 | Waiting for table level lock| INSERT INTO `tb_access_log` VALUES (15643029,""|
| 4452171 | inno | localhost | tempdb | Query | 6 | Waiting for table level lock| INSERT INTO `tb_access_log` VALUES (173947,"70 |
| 4452172 | inno | localhost | tempdb | Query | 15 | Waiting for table level lock| INSERT INTO `tb_access_log` VALUES (9490507,"7 |
| 4452173 | inno | localhost | tempdb | Query | 30 | Waiting for table level lock| INSERT INTO `tb_access_log` VALUES (3271602,"4 |
+---------+---------+-----------+---------+---------+--------+-----------------------------+----------------------------------------------+
c、调整myisam有关参数后导入
[root@GZ-APP-BAK01 tmp]# time myloader -u innobk -p InnoBK -B tempdb -t 6 -d /backup/tmp -v 3
** Message: 6 threads created
** Message: Creating table `tempdb`.`tb_mobile_access_log`
** Message: Thread 1 restoring `blossom`.`tb_mobile_access_log` part 3
** Message: Thread 6 restoring `blossom`.`tb_mobile_access_log` part 6
** Message: Thread 2 restoring `blossom`.`tb_mobile_access_log` part 5
** Message: Thread 3 restoring `blossom`.`tb_mobile_access_log` part 4
** Message: Thread 4 restoring `blossom`.`tb_mobile_access_log` part 1
** Message: Thread 5 restoring `blossom`.`tb_mobile_access_log` part 2
** Message: Thread 6 shutting down
** Message: Thread 5 shutting down
** Message: Thread 1 shutting down
** Message: Thread 2 shutting down
** Message: Thread 4 shutting down
** Message: Thread 3 shutting down
real 266m28.903s
user 0m6.008s
sys 0m1.681s
###调整以下相关参数，后尝试再次导入，
concurrent_insert AUTO 改成 ALWAYS
bulk_insert_buffer_size 8388608 改成 256M
myisam_sort_buffer_size 67108864 改成 128M
[root@GZ-APP-BAK01 tmp]# time myloader -u innobk -p InnoBK -B tempdb -t 6 -o -d /backup/tmp -v 3
** Message: 6 threads created
** Message: Dropping table (if exists) `tempdb`.`tb_mobile_access_log`
** Message: Creating table `tempdb`.`tb_mobile_access_log`
** Message: Thread 1 restoring `blossom`.`tb_mobile_access_log` part 3
** Message: Thread 2 restoring `blossom`.`tb_mobile_access_log` part 6
** Message: Thread 3 restoring `blossom`.`tb_mobile_access_log` part 5
** Message: Thread 4 restoring `blossom`.`tb_mobile_access_log` part 4
** Message: Thread 6 restoring `blossom`.`tb_mobile_access_log` part 1
** Message: Thread 5 restoring `blossom`.`tb_mobile_access_log` part 2
** Message: Thread 2 shutting down
** Message: Thread 1 shutting down
** Message: Thread 6 shutting down
** Message: Thread 5 shutting down
** Message: Thread 3 shutting down
** Message: Thread 4 shutting down
real 253m42.460s ###此时导入时间并无明显减少
user 0m5.924s
sys 0m1.637s
2、基于innodb引擎的导出导入
a、表未分块导出，数据文件大小为3.9GB
[root@GZAPP tmp]# ls -hltr
total 3.9G
-rw-r--r-- 1 root root 1.8K Jul 24 00:09 bscom.tb_message-schema.sql
-rw-r--r-- 1 root root 3.9G Jul 24 00:25 bscom.tb_message.sql
-rw-r--r-- 1 root root 215 Jul 24 09:14 metadata
###下面使用6个线程导入，实际上可以看到，只有1个线程在工作，因为数据文件只有1个
[root@GZAPP tmp]# myloader -u inno -p xxx -B tempdb -t 6 -d /backup/tmp -v 3
** Message: 6 threads created
** Message: Creating table `tempdb`.`tb_message`
** Message: Thread 1 restoring `bscom`.`tb_message` part 0
** Message: Thread 5 shutting down
** Message: Thread 2 shutting down
** Message: Thread 6 shutting down
** Message: Thread 3 shutting down
** Message: Thread 4 shutting down
b、表分块导出
[root@GZAPP tmp]# mydumper -u inno -p xxx -B bscom -T tb_message -F 500 -o /backup/tmp/
[root@GZAPP tmp]# ls -hltr
total 3.9G
-rw-r--r-- 1 root root 1.8K Jul 24 09:55 bscom.tb_message-schema.sql
-rw-r--r-- 1 root root 478M Jul 24 09:55 bscom.tb_message.00001.sql
-rw-r--r-- 1 root root 478M Jul 24 09:55 bscom.tb_message.00002.sql
-rw-r--r-- 1 root root 478M Jul 24 09:55 bscom.tb_message.00003.sql
-rw-r--r-- 1 root root 478M Jul 24 09:55 bscom.tb_message.00004.sql
-rw-r--r-- 1 root root 478M Jul 24 09:55 bscom.tb_message.00005.sql
-rw-r--r-- 1 root root 478M Jul 24 09:55 bscom.tb_message.00006.sql
-rw-r--r-- 1 root root 478M Jul 24 09:55 bscom.tb_message.00007.sql
-rw-r--r-- 1 root root 481M Jul 24 09:55 bscom.tb_message.00008.sql
-rw-r--r-- 1 root root 135 Jul 24 09:55 metadata
-rw-r--r-- 1 root root 93M Jul 24 09:55 bscom.tb_message.00009.sql
###下面尝试使用6线程导入，可以看到有6个线程在并发导入
[root@GZAPP tmp]# myloader -u inno -p xxx -B tempdb -t 6 -d /backup/tmp/ -v 3
** Message: 6 threads created
** Message: Creating database `tempdb`
** Message: Creating table `tempdb`.`tb_message`
** Message: Thread 2 restoring `bscom`.`tb_message` part 5
** Message: Thread 1 restoring `bscom`.`tb_message` part 9
** Message: Thread 3 restoring `bscom`.`tb_message` part 1
** Message: Thread 4 restoring `bscom`.`tb_message` part 8
** Message: Thread 5 restoring `bscom`.`tb_message` part 4
** Message: Thread 6 restoring `bscom`.`tb_message` part 6
** Message: Thread 1 restoring `bscom`.`tb_message` part 7
** Message: Thread 6 restoring `bscom`.`tb_message` part 3
** Message: Thread 2 restoring `bscom`.`tb_message` part 2
** Message: Thread 3 shutting down
** Message: Thread 5 shutting down
** Message: Thread 4 shutting down
** Message: Thread 1 shutting down
** Message: Thread 2 shutting down
** Message: Thread 6 shutting down
3、小结
a、mydumper在导出的时候可以根据服务器可用资源来合理地设置线程数。
b、mydumper在导出的时候尽可能地指定chunk-filesize或者rows参数以分块导出。
c、myloader在针对myisam引擎时建议调整相关参数至合理值以提高无法提高性能，主要是表级锁的问题。
d、myloader在针对innodb引擎时建议调整参数至合理值以提高性能，如以下参数等：
innodb_buffer_pool_size
innodb_flush_log_at_trx_commit
innodb_log_buffer_size
e、通过使用分块导出与导入可以显著利用并发来加快inndbo表导入。
f、注意mydumper导出时不会导出存储过程，函数，触发器等。
