Re: [HACKERS] Help: fmgr_info: function 0: cache lookup failed

Tom, was this dealth with?

> "D'Arcy" "J.M." Cain <darcy(at)druid(dot)net> writes:
> >>>> I tried just setting oprcanhash to true but that didn't do it. Can
> >>>> you suggest what fields I need to look at in pg_operator?
> >>
> >> oprrest and oprjoin
>
> > OK, I did this and it worked. I'll go work on the documentation now.
>
> OK, I see the problem: btreesel() and friends blithely assume that the
> operator used in an index will have a selectivity function (oprrest).
>
> I can see two reasonable fixes:
> * Default to an 0.5 estimate if no oprrest link (this is what the
> optimizer does for operators that have no oprrest).
> * Generate an error message along the lines of "index operators must
> have a restriction selectivity estimator", if we think that they
> really really oughta.
>
> I'm not sure which way to jump. The former would be more friendly for
> people just starting to develop index support for a new data type ...
> but then they might never realize that lack of an estimator is hurting
> performance for them. Comments?
>
> regards, tom lane
>
>

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