Several reasons, actually, but this post, I, Cringely . The Pulpit . Data Debasement | PBS, gets to one of them.
Hash tables, on the other hand...
Thanks in part to Larry Ellison's hard work and rapacious libido, databases are to be found everywhere. They lie at the bottom of most web applications and in nearly every bit of business software. If your web site uses dynamic content, you need a database. If you run SAP or any ERP or CRM application, you need a database. We're all using databases all the time, whether we actually have one installed on our personal computers or not.Not only is a (relational) database (server) hard to back up reliably, a processing bottleneck, and a single point of failure, it also doesn't distribute worth a damn, so it doesn't scale.
But that's about to change.
We're entering the age of cloud computing, remember? And clouds, it turns out, don't like databases, at least not as they have traditionally been used.
This fact came out in my EmTech panel and all the experts onstage with me nodded sagely as my mind reeled. No database?
No database.
Hash tables, on the other hand...