> In that case, this code is worse than before as far as developing plans
> goes. The selectivity estimator needs to be taught about what BETWEEN
> means. Currently it recognizes (x > foo AND x < bar) as a range query
> --- a BETWEEN node is obviously much easier to recognize, but you still
> have to add code to do it.
I simply multiple the results of the left, right and common expression
after sending them through clause_selectivity() ?
