Re: Query optimization problem

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> SELECT d1.ID, d2.ID
> FROM DocPrimary d1
> JOIN DocPrimary d2 ON d2.BasedOn=d1.ID
> WHERE (d1.ID=234409763) or (d2.ID=234409763)
>
> ...you're going to scan d1, scan d2, and then join the results. The
> scan of d1 is going to produce different results depending on whether
> you evaluate or not d1.ID=234409763, and the scan of d2 is going to
> produce different results depending on whether or not you evaluate
> d2.BasedOn=234409763.

Well I just realised you can't use d2.BasedOn in scanning d1 here. I
don't know what exactly I had in mind previously, but in any case, sorry
for the noise.

I hope the optimiser effort control still hold water nonetheless…
--
dim