Typical fanboy bluster. What's dishonest about the criticism, be specific? What you really mean to say is that most MySQL users use it because it is there and take it as it has been configured for them. MySQL is the storage platform for people who do not know about databases and probably only use it because some blogging product requires them to.
You just made his point and rather succinctly too.
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.
Even when a company like Google or Facebook uses "mysql", it's not stock Oracle MySQL -- which is what people are going to download and use when they hear that MySQL is good enough because major companies use it. This is an unfortunate situation caused by most distributions still favoring stock mysql over percona, and Oracle refusing to incorporate patches even when they're plenty of evidence that people who know what they're doing want those patches.
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.
Up until very recently Twitter was still using stock MySQL 5.0.45 (which I believe is from 2007) nearly everywhere in production. The notion that MySQL requires a highly patched version with a world class development team to maintain is a myth. Facebooks patches are made public and are often incorporated into MariaDB and/or Percona forks. Oracle usually goes their own way on implementing changes from the community.
Not at all. Like I say above, right tool for the job. I don't doubt that all those companies use MySQL for something, indeed probably every large company in the world has at least one instance of it somewhere.
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.
PS the cost of not losing "ANY data for ANY reason" is effectively infinite. You make a call on what data loss would cost your business then you decide how likely each scenario is and that gives you your budget. Datacentre disruptions I have been personally involved with include workmen digging up fibre (several times actually), deliberate vandalism of cable (during May Day riots), fire in the generator room (a couple of times), large truck losing control and driving through the walls, flooding, and several more. No one of these scenarios was sufficient by itself to hurt us because we had mitigated them. But 2 happening together, then yeah, there is a significant possibility that some data loss would occur (e.g. replication to datacentre B is disrupted, then datacentre A is catastrophically lost). The cost of protecting against that however is prohibitive.
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
