As I remember, Vadim wrote the storage engine for 5.0 and it has not been ported to 5.1. I’ll ask him to post a reply here, but I think it needs to be ported to 5.1, which we would look for sponsorship to do. The 5.1 storage engine API is not fully compatible with the 5.0 API.
Vadim corrected me, there is a 5.1 plugin storage engine. But he says he hasn’t tested it for years.
Obviously I am not an expert in this topic. The guys who are experts in it are very busy and are not very active on this forum. But if you can’t solve the problem, place an inquiry on percona.com and we can give you an estimate of what it would take for us to solve this.
I have the same problem with SphinxSE 0.9.9 and MYSQL 5.1.41.
It’s the default version of MYSQL on Ubuntu 10.04 LTS.
It compiles fine and works, although this message is always in the error log “[Warning] Storage engine ‘SPHINX’ has conflicting typecode. Assigning value 42.” and queries through the plugin fail under high load, when that happens connection gets dropped and CPU usage goes to 100% on MySQL.