Whenever I say something like “you do not need sharding for 95% application” or “You do not need other than Innodb storage engine for 95% of application” I get a lot of feedback, hey it does not apply to my case.  People are passionate in proving me wrong based on the fact it does not apply to their case, and I would guess because it does not apply to a lot of people they know too.

This is a very common trap of extending the facts about world around us to the broader group.   For some of the issues we seems to grasp these facts, for example  the fact 95% people speak English in the neighborhood I live in would not translate to the same amount of people in the world knowing the language. And yet for other, for example professional questions we may feel the world in whole is similar to world around us. It is not.

Bay Area in particular is a concentration of a lot of very large web sites –  Google, Yahoo, Facebook, Twitter  are all from here. They employ a lot of staff and so if you’re working professionally in Web space chances are you work on one of these high scale systems or have buddies which work where.

But if you look at number as a whole – there are many millions of small applications out there, such as this web site, many hosted on virtual hosting with very modest  performance needs.

You well might be exceptional groups and your experiences may not translate to world as a whole.  This also means you always have to be careful applying claims to yourself if they apply to large portion of the population.   For example I bet the salary over 95% of people in the world would not go that far in Bay Area ?