Downgrading MySQL on Mac OS X
I just tried installing MySQL 5.5 on Snow Leopard, using the community
.dmg file from mysql.com. I decided to stick with 5.1, so removed 5.5
and then ran the installer for 5.1.55. It gave me this delightful
MySQL 5.1.55-community for Mac OS X can't be installed on this disk. A newer version of this software already exists on this disk.
What a crock. Even though 5.5 has been removed, it refuses to let you
install an earlier version. To persuade it that 5.5 really has gone, you
need to delete a
.plist file that the installer leaves behind.
This command should fix it:
$ sudo rm /var/db/receipts/com.mysql.mysql.*
We should all be using Postgres.