Well THAT was fun.

A few days after switching the entire site to MySQL, I discover that there’s performance issues. Digging into it more, I discover that actually, IIS processes are crashing, consuming 100% of the available CPU and that’s making everything slow and crashy,

Then I dig in more and discover that it only happens when posting interesting UTF-8 characters (like ß or ü or “smart quotes” or whatever) to the database. Initially I thought it was to do with mod_proxy not forwarding request bodies, but that turned out to be a red herring.

Looong and frustrating day yesterday only to discover that the MySQL ODBC connector comes in two flavours, (a) and (w). I had (a) installed. Apparently, although they look identical and have identical options in the ODBC manager, only one of them can actually do Unicode characters. *headdesk*.

So everything should be fine again now.