I spent a few hours trying to track down this error before finally finding the problem. Googling around you see posts saying the fix is to uninstall and rebuild the mysql gem against your local install of mysql.
For me this did not fix my problem. I encountered the same error, but caused by installing Mysql 5.5 on a new OS X environment. Aparently, the current stable version for rails/osx development is Mysql 5.1.
If you have installed 5.5:
1) uninstall following these instructions.
2) Download MySQL 5.1 here and run through the install for db, preference panel, and startup item.
Frequently applications need to have different settings between development, staging, and production environments. Usually there are default settings stored with in source control, but when it comes time to deploy to one of your environments you want to override these defaults with environment specific settings. For certain properties you might also need to modify them while the appliction is running, which can get be become problematic if you have to restart your application server every time you change a property.
A way to avoid this in Java is by using Apache Commons Configuration which provides:
1) Property Overriding - Depending upon how you define the order your property files are ordered in your xml config file, a property can be override.
2) Dynamically Reload Properties - Commons configuration will watch files for modifications and automatically load any changes that are made.
To get overriding behavior use OverrideCombiner in your configuration file, and the define your properties in descending order of precedence:
Finally, in your code wrap your configuration in a property manager class that makes use of the CombinedConfiguration class:
RT @zedshaw: Interesting article by Marc Fleury: http://tinyurl.com/2b7ebk3 Is this still true in the EU?
Into my second week of full-time mac development after 4+ years on windows. My dock is looking serious.