Re: Workaround: Planner preference for tsquery filter vs. GIN index in fast text search

On 04/20/2014 07:46 AM, Oleg Bartunov wrote:
> btw, 9.4 should be wiser in case of rare+common terms, thanks to GIN
> fast scan feature.

Indeed, although we didn't actually do anything to the planner to make 
it understand when fast scan helps. Doing something about cost 
estimation is still on the 9.4 Open Items list, but I don't have any 
ideas on what to do about it, and I haven't heard anything from 
Alexander about that either. That means that the cost estimation issue 
Laurence saw is going to be even worse in 9.4, because GIN is going to 
be faster than a seq scan in more cases than before and the planner 
doesn't know about it.

- Heikki