Comment 21 for bug 1251123

@Morgan Fainberg,

Oh, I got it now, sorry for my misunderstanding, and thanks for the so detailed explanation.

In fact, we are hesitating about using Mysql or mysql backend on the premise that we can't change default TTL because users already using it for a long time. The problem to mysql is updating user password takes too much time, the problem to memcache is reported here.