Can anyone point me to any data that shows validates the scalability promises of the MySql database ? Specifically I am looking for real life examples of applications running MySql server and handling millions of transactions. I need this data to sometimes convince some of our customers that the LAMP platform is production grade.
You may want to ask at http://superuser.stackoverflow.com as the sysadmins will have a better idea about scalability.
My concern with MySQL now is that is has basically forked. Since Sun took it over I haven't been as impressed, and now that Oracle controls it I have more concern, so I am moving to Postgres.
You may want to look at what the future of MySQL is going to be before completely settling on it.
Here is a starting point that may be helpful:
http://ostatic.com/blog/monty-widenius-mysql-founder-forecasts-the-mysql-future You will want to at least be able to have answers about what you expect the future to hold, as your investors may ask, and not knowing would be a major problem.
Before you ask about scalability you will want to rephrase to give more specifics. For example, millions of transactions per day or hour? What percentage of queries will be inserts/updates and which would be selects? What kind of hardware will you be using, and how many machines?
I would hope that you will have a competent dba to take care of the database, as the administration of this will be a challenge.
Also, in my experience the scalability problems I faced was due to the webserver, mysql could handle whatever I sent to it, but the webserver would reach limits and some connections would fail due to that.
Craigslist uses MySQL. Check out these slides from a Craigslist engineer who describes their requirements and how they scaled.
There are many companies currently running MySQL in production. Most of them had to build on top of MySQL to sustain the capacity they required: Facebook, Friendfeed, YouTube, Flickr, 37Signals, etc.
http://bret.appspot.com/entry/how-friendfeed-uses-mysql http://www.youtube.com/watch?v=ZW5_eEKEC28 http://dev.mysql.com/tech-resources/interviews/david-heinemeier-hansson-rails.html However, these sites are much bigger than most, so MySQL out of the box is a reasonable choice. However, sometimes that is not the main issue. For example, if your customers are a Microsoft shop (Windows, MSSQL, .Net, etc.), they'll have a hard time with the sysadmin experience required for LAMP because they don't have the facilities (and personnel) to deal with it.
Also, whole Wikipedia and it's sister projects run on MySQL.