mysql 5.5参数–innodb_read(write)_io_threads

### 5.1
# innodb_file_io_threads
# The number of file I/O threads in InnoDB.
# Normally, this should be left at the default value of 4, but disk I/O on Windows may benefit from a larger number.
# On Unix, increasing the number has no effect; InnoDB always uses the default value. ### 5.5
innodb_read_io_threads=4 # (default)
innodb_write_io_threads=4 # (default)

——————————————–
root@127.0.0.1 : (none) 10:46:59> show variables like ‘innodb_%io%threads’;
+————————-+——-+
| Variable_name | Value |
+————————-+——-+
| innodb_read_io_threads | 4 |
| innodb_write_io_threads | 4 |
+————————-+——-+
2 rows in set (0.00 sec)root@127.0.0.1 : (none) 10:47:09> select version();
+————–+
| version() |
+————–+
| 5.5.7-rc-log |
+————–+
1 row in set (0.00 sec)
##### show engine innodb status on V 5.5###
FILE I/O
——–
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 state: waiting for completed aio requests (log thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: waiting for completed aio requests (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)
I/O thread 9 state: waiting for completed aio requests (write thread)
Pending normal aio reads: 0 [0, 0, 0, 0] , aio writes: 0 [0, 0, 0, 0] ,
ibuf aio reads: 0, log i/o’s: 0, sync i/o’s: 0
Pending flushes (fsync) log: 0; buffer pool: 0
153 OS file reads, 3 OS file writes, 3 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s##### show engine innodb status on V5.1——–
FILE I/O
——–
I/O thread 0 state: waiting for i/o request (insert buffer thread)
I/O thread 1 state: waiting for i/o request (log thread)
I/O thread 2 state: waiting for i/o request (read thread)
I/O thread 3 state: waiting for i/o request (write thread)
Pending normal aio reads: 0, aio writes: 0,
ibuf aio reads: 0, log i/o’s: 0, sync i/o’s: 0
Pending flushes (fsync) log: 0; buffer pool: 0
24 OS file reads, 138506 OS file writes, 6249 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
#我们发现，
#在5.1的4个FILE_iO 线程包括:
insert buffer thread
lo开发云主机域名g thread
read thread
write thread

#而在5.5, 总共有10个FILE_IO线程
(insert buffer thread) * 1
(log thread) * 1
(read thread) * 4
(write thread) * 4 有了更多读写线程的支持，也相应地增加了INNODB更大的并发能力；
期待5.5版本的更快成熟；

相关推荐: MySQL 字符集utf8、utf8mb3、utf8mb4

首先想要了解MySQL的字符集，就需要去官方文档看看字符集是如何介绍的。英语不错的话，看官方文档应该是没问题。在搜索框里搜一下就可以找到相关的解释。我就在这里整理一下，以便后期查看。字符集在官方文档下面这一章节：Chapter 10 Character Set…