On Thu, 2019-05-02 at 01:05 -0400, Tom Lane wrote: > Sergey Koposov <skopo...@cmu.edu> writes: > > > > On Thu, 2019-05-02 at 00:36 -0400, Tom Lane wrote: > > > > > > What sort of selectivity estimator have you got attached to that custom > > > operator? > > > > This is the code, but basically it is just a constant based on the search > > radius (which is the leftmost float argument of the operator) > > https://github.com/segasai/q3c/blob/361140d4f1f36bf16c9c53721d1c4f03cb4de930/q3c.c#L89 > Hm, that query should be paying attention to join selectivity, and > you don't have a join selectivity function. > > I think that it applies the restriction selectivity while > estimating the size of the bitmap scan's output. But that's not > what's going to determine the estimated size of the join output. > > Too tired to look at this really closely, but I think basically > the inconsistency boils down to the lack of consistency between > your restriction estimator (1e-12) and your join estimator > (which, since you haven't got one, is going to default to > something way larger, possibly 0.5).
Thanks very much checking, Tom! Adding the join selectivity estimator fixed the problem. I think I initially tried it, but it wasn't clear whether it was called at all or not. Plus I was confused by the fact that the bitmap scan prediction showed 1 row, so it looked like the selectivity worked. Sergey
