Steve T <steve(at)retsol(dot)co(dot)uk> writes:
> So in my case, I can now see that the join_collapse_limit has indeed
> been set back to 8 - but I'm still getting the improved query speed.
So that was in fact unrelated to your problem. Maybe it was just that
auto-analyze caught up with changes you'd made to the table contents?
regards, tom lane