Description of problem: I've seen queries on the key/value table that end up doing 20 self joins which mysql doesn't handle well. Couple things to try here. 1 - Identify possibly problem queries, count the number of joins being built and fail if the joins are over a configured limit. 2 - Implement a timeout so that we don't wait forever on a query.
The Search could be a problem in this regard. By adding more criteria to the search they can ramp up the query to their hearts content pretty much.
since the query plan has been updated this doesn't seem like a problem anymore. closing