Re: BUG #12584: small bug about estimation of rows

Hi,

Thank you for the fix.

2015-01-19 7:06 GMT+09:00, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> t(dot)katsumata1122(at)gmail(dot)com writes:
>> I found a bug about estimating rows without pg_class.reltuples.
>> ...
>> It should be using sizeof(ItemIdData) at line 512, so the estimated rows
>> should be "rows=2260".
>> I could understand ignoring alignment of data here from comment of the
>> source code,
>> but I couldn't find the reason of using sizeof(ItemPointerData) at this
>> point.
>> Usually this would not cause big problem, but it seems odd to me.
>> Is there any reason to use sizeof(ItemPointerData) ?
>
> You're absolutely right, that's a thinko. Adjusted in HEAD. I'm not
> inclined to back-patch it though, since there's a risk of changing
> plan choices which is something we don't like to do in stable branches
> unless the planner is clearly doing the wrong thing.
>
I think it's good to avoid undesirable risk.

Thank you very much again!

regards,
-------------
Tomonari Katsumata