Re: Slow query: bitmap scan troubles

On Wed, Dec 5, 2012 at 9:43 AM, Claudio Freire <klaussfreire@gmail.com> wrote:
> On Wed, Dec 5, 2012 at 2:39 PM, Jeff Janes <jeff.janes@gmail.com> wrote:
>> I'm not sure that this change would fix your problem, because it might
>> also change the costs of the alternative plans in a way that
>> neutralizes things.  But I suspect it would fix it.  Of course, a
>> correct estimate of the join size would also fix it--you have kind of
>> a perfect storm here.
>
> As far as I can see on the explain, the misestimation is 3x~4x not 200x.

It is 3x (14085 vs 4588) for selectivity on one of the tables, "Index
Only Scan using idx_trade_id_book on trade".

But for the join of both tables it is estimate 2120 vs actual 11.

Cheers,

Jeff