Until recently, I've used MySQL for all my database needs in all my server projects.
However, after Oracle came along and bought MySQL, there seems to be some uncertainty about the future of MySQL.
So I'm left wondering whether I should stick to MySQL (which I'm fairly familiar with), or should I switch to something like PostgreSQL. Any thoughts?
A similar thing happened with Sybase and it seemed like a fairly smooth transition. Of course that's not the same situation, but they are similar...
For what it's worth Oracle claims MySQL will be around for a while to come...
MySQL and PostgreSQL are both open-source DBMSs that will continue to be developed by independent parties should their current maintainers (corporate or otherwise) get bored. MySQL already has some interesting forks such as Drizzle which may rise to more prominence if Oracle choose to let the original project stagnate (well, more than Sun did...).
You should choose based on your projects' technical needs rather than nebulous arguments that one or the other is going to ‘win’.
(Personally I definitely think it's a good idea to have experience with both.)
If you're looking for a reason to switch to postgres, "Sunoracle bought MySQL" isn't a good one. MySQL is going to be around for a while.
From Oracle Makes Commitments to ... Users of MySQL:
4.Commitment to enhance MySQL in the future under the GPL. Oracle shall continue to enhance MySQL and make subsequent versions of MySQL, including Version 6, available under the GPL. Oracle will not release any new, enhanced version of MySQL Enterprise Edition without contemporaneously releasing a new, also enhanced version of MySQL Community Edition licensed under the GPL. Oracle shall continue to make the source code of all versions of MySQL Community Edition publicly available at no charge.
...
6. Increase spending on MySQL research and development. Oracle commits to make available appropriate funding for the MySQL continued development (GPL version and commercial version). During each of the next three years, Oracle will spend more on research and development (R&D) for the MySQL Global Business Unit than Sun spent in its most recent fiscal year (USD 24 million) preceding the closing of the transaction.
Even with that, remember, it's GPL. If Oracle does something really dumb, the worst-case scenario is a fork.
If MySQL's working fine for you right now, then there's no reason to switch, unless you need a feature that's only available in other RDMBSs. As for MySQL's future, even if Oracle were to kill it outright at this very moment, the GPL license ensures that MySQL's source will live on. Might have to be called something else (like MariaDB) due to trademarks, but the program itself can't be killed.
On the one hand, I wouldn't take Oracle's promises to continue to develop MySQL too seriously. Any time a company buys out a product that competes with one of their own, they make statements that they will fully support it indefinately. But often a few years (or months) later they quietly pull the product from the market and provide customers with an "upgrade path" to their own product. Let me hasten to add that I don't claim to have any inside track on Oracle or MySQL. This is just a general observation.
That said, if the current version of MySQL meets your needs, then so what if Oracle never makes any further updates ever? There are plenty of people out there using versions of MySQL that are many years old who have never bothered to upgrade to the current version. I'd say just go ahead and use MySQL. If Oracle's support proves weak or even non-existant, and at some point other database products are adding features that you could really use and that Oracle isn't providing, then you might have a reason to migrate. Sure, there might be compatibility problems. But at this point there are a stack of what-if's: What if Oracle doesn't support the product? What if useful new features are added to other products? What if my code isn't compatible? What if Martians invade? etc
MySQL was already in trouble before Oracle bought SUN, development of version 6.0 was canceled, just like version 5.4.
Version 5.1 is supported until the end of this year, 2010-12-31, after that, only extended support is available, but you have to pay for it. No more community patches. Version 5.5 or 5.6 are still not GA, still alpha and/or beta. If you can live without patches, just go on, if want patches but don't want the bill, move on to a different database.
MariaDB (Monty's new product) is using the MySQL-code, his last patches came months after MySQL released it's patches. MariaDB doesn't look too good, it wants to stay very close to the original and has it's dependencies. MariaDB might be in trouble next year for it's support on 5.1 versions.
And all these problems started before Oracle got involved. Many reasons to move away from MySQL, but (imho) Oracle is't the main problem. Oracle wants money and their customers are going to pay, that has been crystal clear from the start.