Tell me, in very busy projects, there are tables of requests for closings, or do they store only summary information?
The question arose, since the project appeared for 300-500 thousand requests per day. Server with a slow hard drive (7200). And on the table of rekvestov (InnoDb), 5-10 slow insert-ins began to appear once every 3-4 hours, for 5-30 seconds of those who are weighing. I unscrewed all that is possible in Mysql, but anyway, sometimes these inser-you pop up. In the table id is the primary key, and another index by time. MySQl version 5.6.
The table now contains 5 million records. There is an option either not to store requests at all, but leave only sessions, or use the type of Memory tables, and merge information at night.