Rob
Sir - I have to congratulate you on having the most coherently summarised and
yet complex list query I have ever seen.
I fear that I will be learning from this problem rather than helping, but one
thing did puzzle me - you've set your random_page_cost to 0.5? I'm not sure
this is sensible - you may be compensating for some other parameter
out-of-range.
--
Richard Huxton