MySQL has a low barrier to entry with some reasonable tools that make it easy to get up and running with a minimum of fuss. For a large swathe of applications it does the job just fine. There's little point in trying to pretend otherwise. Where PostgeSQL really fits in is when the next step is needed, either because the app has outgrown what MySQL can offer or there are some use (edge) cases where PostgreSQL does a better job. Address these areas competently and the world will beat a path to your door.
Exactly. I mean seriously what do Facebook, Twitter, Yelp, LinkedIn, Flickr etc know about storing lots of data.
It seems like Oracle is more concerned about trying to keep mysql less well suited for major deployments, so it can upsell its flagship product. Or else their development process simply doesn't properly accommodate community assistance. Either way, as long as their resistance to community-aided development continues, mysql and oracle/mysql disparagement will continue, not because people hate Oracle, but because Oracle's management of mysql makes it less than ideal for those who simply want a good open source database.
Which is the point of the OP. Anyone who is open to looking at options and who wants a good open source database should look at PostgreSQL.
I doubt any of those example companies you listed even use stock Percona. Facebook for sure has extensive modifications beyond even the publicly available distributions like Percona and MariaDB.
Source: http://tinyurl.com/7adp6fl (PDF)
http://zurlocker.typepad.com/theopenforce/2005/12/googles_us... http://research.google.com/pubs/pub38125.html
You think they are equally going to be okay with losing data ? Or do you want to try again.
Let's add some more companies: 37Signals, DHL, Dropbox, Evernote, UPS, Kayak, LastMinute, Orbitz, Continental, Mint, Quora, Tumblr, Techcrunch, Slashdot, NYT, NBC, Reuters, Wotif, Zappos, Wikipedia, Youtube.
You still think any of these companies would tolerate loss of ANY data for ANY reason ?
For example, taking the first company on your list that actually deals with real stuff in the real world rather than just running a website, DHL, here I see http://www.oracle.com/us/corporate/press/037809 - they're an Oracle shop. I could continue but I think I've proved my point.
So before you get all starry-eyed about these amazing companies and their amazing MySQL installations, understand that you are starting from a false premise. Oracle - for a cost - provides some powerful capabilities (e.g. stretch-RAC[1]). Is it worth the money? Well, it comes back to what your data is worth. This incidentally is why some organizations cling to paper forms - it's cheaper to re-key the data than build out the infrastructure to do it all online...
[1] Tho' if you think you need this, what you probably really need is DB/2 and Sysplex