Installing dbd-mysql for 64-bit binary installation of MySQL
Submitted by Hannes Schmidt on Sat, 06/20/2009 - 18:02.
The dbd-mysql gem assumes (?) an i386 architecture when building the native component of the driver. You'll need to set ARCHFLAGS appropriately and point the build at the installation of MySQL.
sudo env ARCHFLAGS="-arch x86_64" \ gem install mysql -- \ --with-mysql-config=/usr/local/mysql/bin/mysql_config
That should fix it.