Whilst I heartily recommend mySQL, I strongly advise anyone choosing a new database to consider PostgreSQL. I personally found mySQL underspecified; its particularly clumsy at the current version in handling triggers. We ported directly from Oracle 9.x and found the transition to Postgres quite easy; the prediction for mySQL was far more difficult and inelegant/more difficult to maintain. We have found Postgres approximately as stable over the last year as Oracle was in the prior year and have saved approximately £10k in annual Oracle fees.

Note; I have no affiliation with any company or developer or toolset.

Tim Clarke

More specifically, Wells Fargo uses MySQL as part of it's online banking and BofA uses it for risk analysis. The US Navy uses it to distribute bathymetery data to warships. MySQL runs Travelocity's fare engines (airfare, hotels, etc)

I don't know what you call 'enterprise', but there is no doubt that MySQL is used in enterprise situations, particularly in read intensive applications. While Gartner and IDC may not reflect it in there numbers, that's more likely due to the fact that companies don't like to advertise their competitive advantages rather than any lack of deployment.

Open source databases, not only MySQL but also Postgres and Firebird, are serious competitors to Oracle and DB2 in a lot of enterprise situations. And with commercial vendors like EnterpriseDB and Solid providing high-end features like Oracle compatibility and high-availability, open source database are rapidly gaining deployments at the expense of commercial dbs.

Chris.

Personally I feel much better when a mission critical system is built around PostgreSQL database. I think PostgreSQL is already ready for Enterprise -- it has support available from companies like Fujitsu or Sun and also the EnterpriseDB which aims at Oracle compatibility.

As for MySQL... it has its drawbacks. You have to double check all the features work as expected (as you have learned using DB2 or Oracle), otherwise you may be seriousley bitten,

as many of its users have. And get ready for some hacking like reimplementing sequences yourself because AUTO_INCREMENT is not exactly the thing you need, learning to define FOREIGN KEY constraints the right way, so they are not considered just comments by the database or keeping in mind that by default comparisons are case insensitive (unless declared binary/case sensitive locale). These are the things which make some people claim MySQL not ACID compilant. If you intend to use MySQL where data is very valuable, make sure you hire people who really KNOW this specific engine.

Being bitten too many a time I have happily converted to PostgreSQL (together with Oracle).

You have a business to run and you have a choice to make - to buy a bicycle for small change (MySQL) or to acquire a heavy-duty truck for free (PostgreSQL).

According to an analyst firm, Forrester Research, MySQL Enterprise reduces the DBA requirements.

http://www.mysql.com/news-and-events/news/article_1171.html