Here's the funny thing. It doesn't matter anymore. Patrick's question is interesting in an academic sense, but it's mainly a distraction from what really matters. (Hint: What's the official Linux and who really cares? Ubuntu? RedHat? Debian? CentOS?)
Nowadays what matters is the set of available storage engines. InnoDB, Percona's XtraDB, PrimeBase's PBXT, Maria, Falcon, and several others are available or will be soon. I predict that for the foreseeable future, any MySQL distribution or derivative must support the storage engine plug-in API that MySQL 5.1 defined. And since that's the case, it largely won't matter which flavor you using.
Look at what's happened in the world of key/value databases in the last few years. More than a few of them speak the memcached protocol as either their native and default or an optional add-on. I suspect the same thing will be the case here. All MySQL distributions and derivatives will speak the "traditional" MySQL protocol (just like memecached has the old protocol). Some of them, notably Drizzle, will have other (newere, better) protocols available as well (much like memcached has the new binary protocol).
In summary, the choice of MySQL version or derivative won't matter as much as you might think because they'll have the same Storge Engine plug-ins available (thanks to the shared plugin-in API), they'll all speak a common protocol (this may not be true for replication--watch that area closely), and will largely offer the same subset of SQL and SQL extensions.
They'll all be supported by different groups/companies (including some "database appliance" vendors), will all be tuned differently and aimed at slightly different uses cases, and will certainly benefit from a lot of cross-pollination.
That doesn't sound so bad to me.
The fact that nobody can point to the "real" MySQL in a few years just won't matter. Does anyone ask (anymore) which is the "real" Linux? Nope. And for very similar reasons. Think of MySQL as "kernel" and Storage Engine as "filesystem" and you'll realize we've been down this road before.
We're looking at the upgrade from 5.0 to 5.1 soon at Craigslist and don't know if we'll be using InnoDB or XtraDB yet. Time will tell.
See Also: The New MySQL Landscape, which I wrote a few months back--before a good chunk of the MySQL team had left Sun.
Posted by jzawodn at March 31, 2009 07:23 AM