Re: RT3.4 query needed a lot more tuning with 9.2 than it did with 8.1

On Mon, May 13, 2013 at 4:14 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> The planner is estimating this the outer side of this nested loop will
>> produce 33 rows and that the inner side will produce 1. One would
>> assume that the row estimate for the join product couldn't be more
>> than 33 * 1 = 33 rows, but the planner is estimating 62335 rows, which
>> seems like nonsense.
>
> You know, of course, that the join size estimate isn't arrived at that
> way. Still, this point does make it seem more like a planner bug and
> less like bad input stats. It would be nice to see a self-contained
> example ...

Yeah, I remember there have been examples like this that have come up
before. Unfortunately, I haven't fully grokked what's actually going
on here that allows this kind of thing to happen. Refresh my memory
on where the relevant code is?

--
Robert Haas
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