Re: performance regression in 9.2 CTE with SRF function

2013/2/11 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
>>> no, there is strange estimation
>>>
>>> SubPlan 2
>>> -> CTE Scan on pl pl_1 (cost=0.00..468.59
>>> rows=89000 width=4) (actual time=0.023..8.379 rows=566 loops=1000)
>>> Output: foo(pl_1.a)
>
> Nothing strange about it. 89 rows out from the underlying CTE (which
> appears to be dead accurate) times 1000 for the SRF's expansion.
>
>> respective why estimation is unstrable
>
> It isn't --- you are looking at two different subplans there, one with
> a SRF in it and one without.

ok, I understand now

Thank you

Regards

Pavel

>
> regards, tom lane