Working on a test case with sysbench, I encountered this: [crayon-5c0a761e07fe2465164286/] I was really surprised. First, and the most important, id is a primary key and the rand() function should produce just one value. How come it returns two rows? Second, why is the response time 0.30 sec? That seems really high for a primary [&]

https://www.percona.com/blog/2018/12/05/nondeterministic-functions-in-mysql-i-e-rand-can-surprise-you/