it is slow,because sql loop locked until mysql dead

Question

 

I'm sorry, my English is not good to say, send a picture to the program authors look at, hope you can understand I want to express the meaning of this system is very good, but do not know how much he can carry the largest data

Comments

Can you please post the output of:

EXPLAIN SELECT COUNT(DISTINCT (userid) ) FROM qa_posts;

Also, what is the running time of:

SELECT COUNT(DISTINCT (userid) ) FROM qa_posts;

Thanks!

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I replaced a host, I found that he can continue to work, but do not know why the original host can not work. The same configuration.