MySQL5.7 在线调整Innodb

在之前的版本,调整Innodb_Buffer_Pool_size大小必须重启MySQL进程才可以生效,如今在MySQL5.7里,可以直接动态设置,方便了很多。

这个功能应用的场景:
一、机器增加内存,DBA粗心大意忘记调大Innodb_Buffer_Pool_size了
二、工作交接,新来的DBA发现前任DBA设置的Innodb_Buffer_Pool_size不合理

需要注意的地方,在调整Buffer_Pool期间,用户的请求将会阻塞,直到调整完毕,所以请勿在白天调整,在凌晨3-4点低峰期调整。

调整时,内部把数据页移动到一个新的位置,单位是块。如果想增加移动的速度,需要调整innodb_buffer_pool_chunk_size参数的大小,默认是128M。

例(把BP 128M增大为384M):

mysql> SELECT @@innodb_buffer_pool_size;

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

| @@innodb_buffer_pool_size |

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

|                134217728 |

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

1 row in set (0.00 sec)

mysql> SELECT @@innodb_buffer_pool_chunk_size;

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

| @@innodb_buffer_pool_chunk_size |

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

|                      134217728 |

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

1 row in set (0.00 sec)

mysql> SET GLOBAL innodb_buffer_pool_size=402653184;

Query OK, 0 rows affected (0.01 sec)

mysql> SELECT @@innodb_buffer_pool_size;

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

| @@innodb_buffer_pool_size |

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

|                402653184 |

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

1 row in set (0.00 sec)


innodb_buffer_pool_chunk_size的大小,计算公式是innodb_buffer_pool_size / innodb_buffer_pool_instances

比如现在初始化innodb_buffer_pool_size为2G,innodb_buffer_pool_instances实例为4,innodb_buffer_pool_chunk_size设置为1G,那么会自动把innodb_buffer_pool_chunk_size 1G调整为512M,例:
./mysqld --innodb_buffer_pool_size=2147483648 --innodb_buffer_pool_instances=4
--innodb_buffer_pool_chunk_size=1073741824;

mysql> SELECT @@innodb_buffer_pool_size;

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

| @@innodb_buffer_pool_size |

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

|                2147483648 |

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

1 row in set (0.00 sec)

mysql> SELECT @@innodb_buffer_pool_instances;

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

| @@innodb_buffer_pool_instances |

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

|                              4 |

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

1 row in set (0.00 sec)

# Chunk size was set to 1GB (1073741824 bytes) on startup but was

# truncated to innodb_buffer_pool_size / innodb_buffer_pool_instances

mysql> SELECT @@innodb_buffer_pool_chunk_size;

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

| @@innodb_buffer_pool_chunk_size |

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

|                      536870912 |

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

1 row in set (0.00 sec)


监控Buffer Pool调整进程

mysql> SHOW STATUS WHERE Variable_name='InnoDB_buffer_pool_resize_status';

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

| Variable_name                    | Value                            |

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

| Innodb_buffer_pool_resize_status | Resizing also other hash tables. |

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

1 row in set (0.00 sec)


查看错误日志:
(增大)

[Note] InnoDB: Resizing buffer pool from 134217728 to 4294967296. (unit=134217728)

[Note] InnoDB: disabled adaptive hash index.

[Note] InnoDB: buffer pool 0 : 31 chunks (253952 blocks) was added.

[Note] InnoDB: buffer pool 0 : hash tables were resized.

[Note] InnoDB: Resized hash tables at lock_sys, adaptive hash index, dictionary.

[Note] InnoDB: completed to resize buffer pool from 134217728 to 4294967296.

[Note] InnoDB: re-enabled adaptive hash index.


(减少)

[Note] InnoDB: Resizing buffer pool from 4294967296 to 134217728. (unit=134217728)

[Note] InnoDB: disabled adaptive hash index.

[Note] InnoDB: buffer pool 0 : start to withdraw the last 253952 blocks.

[Note] InnoDB: buffer pool 0 : withdrew 253952 blocks from free list. tried to relocate 0 pages. (253952/253952)

[Note] InnoDB: buffer pool 0 : withdrawn target 253952 blocks.

[Note] InnoDB: buffer pool 0 : 31 chunks (253952 blocks) was freed.

[Note] InnoDB: buffer pool 0 : hash tables were resized.

[Note] InnoDB: Resized hash tables at lock_sys, adaptive hash index, dictionary.

[Note] InnoDB: completed to resize buffer pool from 4294967296 to 134217728.

[Note] InnoDB: re-enabled adaptive hash index.

--------------------------------------分割线 --------------------------------------

Ubuntu 14.04下安装MySQL

《MySQL权威指南(原书第2版)》清晰中文扫描版 PDF

Ubuntu 14.04 LTS 安装 LNMP Nginx\PHP5 (PHP-FPM)\MySQL

Ubuntu 14.04下搭建MySQL主从服务器

Ubuntu 12.04 LTS 构建高可用分布式 MySQL 集群

内容版权声明:除非注明,否则皆为本站原创文章。

转载注明出处:https://www.heiqu.com/4440bd832e5ccd0fcaf1f035b7aa2dbe.html