mysql中的最大连接数就是请求数吗？那IOPS又表示什么意思呢？

Question

想购买阿里云的RDS mysql，想请教下最大连接数是请求数吗？如下图，600最大可支持连接数，那一个页面查询30次，20个人同时请求，数据库不就超载了么？（内存2400MB，专用数据服务器，只能支持20个人，不敢想象。。。。。）

另外IOPS1200，又表示什么呢？

Answer 1

Number of connections:

就好比你用navicat去连mysql，同时支持600个用navicat去连的用户，超过600个的下一个就需要等待了，这里并不是说只能保持600个用户同时访问，因为你数据库和你应用之间肯定隔着中间件，而中间件中的连接池会帮你管理好每个连接，一般如果代码写的好事物控制得当，一个事物完成连接会被连接池收回重复利用，所以不是说一个用户登录你的系统或网站就一直占用着。

IOPS:

IO并发数，也就是存储上对于每秒IO的并发数的支持。

Answer 2

IOPS (Input/Output Operations Per Second), which is the number of read and write (I/O) operations per second, is mostly used in databases and other situations to measure the performance of random access. The IOPS performance of the storage side is different from the IO of the host side. IOPS refers to the number of accesses issued by the host per second that the storage can accept. An IO of the host requires multiple accesses to the storage to be completed. For example, when the host writes a minimum data block, it also needs to go through three steps: "sending a write request, writing data, and receiving a write confirmation", that is, three storage-side accesses.

In fact, it is easy to understand. A connection may require more than one SELECT and more than one IO each time