Twitter certainly had such an easy win when, while at a fraction of the scale the service now operates at, one of their engineers rewrote their in-house Ruby-based message queue in Scala. That was great, but it was scaling in the small. Twitter is still fighting an uphill battle to scale in the large, because doing so is about much, much more than which technology you choose.

So says Alex Payne in his post Node and Scaling in the Small vs Scaling in the Large (emphasis mine).

That’s not a knock on Twitter, per se. Alex’ larger point is that scaling is not just about hardware OR software. Instead it’s a complicated mix of the two, with a lot of testing, and at least as much magic thrown in.

[Via Saidimu]

From the Future of Web Apps 2008 conference.

PHP supports more than a dozen database setups, including the SQLite library bundled with PHP 5. That’s a lot of databases, and each one has its own connection syntax and server-specific functions.

So what happens when you want to be able to swap one database for another? You turn to an abstraction library, such as PDO.

In Learning PHP Data Objects, Dennis Popel takes you through the process of building an application using PDO with MySQL and SQLite.

Aimed squarely at PHP developers who are new to PDO, Popel covers how to make connections, handle errors, and use prepared statements with PDO. He also discusses transactions, MVC development, and the appropriateness of using PDO versus other abstraction libraries.

Where Learning PHP Data Objects shines, however is in its code examples. They are easy to follow, and Popel smartly alerts readers to potential gotchas in developing the sample application.

The book assumes an understanding of OOPHP — necessary because PDO is entirely object-oriented. To get the most out of it, you should be familiar with object-oriented principles and syntax. While Appendix A does give readers a quick overview of OOPHP, for a more thorough treatment, you’ll need to look elsewhere.

It’s a solid, though not quite perfect book. For example, Popel only sort-of mentions a potentially huge gotcha: when you may need to specify a unix_socket parameter in the connection string. It’s a problem I think would be common enough and confusing enough to discuss and demonstrate. I also think Popel could have been a bit clearer about when and why to use PDOStatement->closeCursor().

Those are minor quibbles however, easily solved by consulting the documentation or doing a Google search. Overall, this book is nice introduction to the whys and hows of using PDO to develop database driven applications.