Our website has been chugging along nicely for years running mysql 4.0.27 when I suddenly thought it might be high time to upgrade into the present.
Of course the suggested upgrade path to 5.x from 4.0.x is to upgrade to 4.1 first and then to 5.x
But of course mysql just ended support for 4.x and I can't find its downloads on their site.
Is it safe to assume that since my database is just being used to serve up content and not handling stuff like ecommerce transactions or, I dunno, air traffic control, that my upgrade path would be like this:
Take the site down for maintenance (returning search engine friendly 503 error codes).
Export my site's content tables with mysqldump.
Eradicate mysql 4.0.27 from the server.
With no mysql around, do a clean install of mysql 5.x.
Create the users and then import my site's tables?
Yes, the changed password encryption method is the main problem when doing the jump from 4.0 to 5.x. You should try to use the new password method as it is more secure then the previous one.
My advice would be to first install 5.x, and only when everything works flawlessly remove 4.0.27. In that way it is less stressful to go back to a working situation in case the upgrade doesn't work as expected. Two MySQL versions should be able to coexist as long as you assign different TCP/IP port numbers to each of the instances and use separate data directories.