Re: Plan stability versus near-exact ties in cost estimates

From: "Albe Laurenz" <laurenz(dot)albe(at)wien(dot)gv(dot)at>
To: "Tom Lane *EXTERN*" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Plan stability versus near-exact ties in cost estimates
Date: 2012-04-21 08:33:43
Message-ID: D960CB61B694CF459DCFB4B0128514C2049FCE82@exadv11.host.magwien.gv.at
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Tom Lane wrote:
>>> Um, that is what the proposed patch does.

>> I was referring to the first two lines that the patch removes.
>> I guess I don't understand why they should go.

> What we'd have left after the proposed removal is
>
> if (new_path->rows < old_path->rows)
> remove_old = true; /* new dominates old */
> else
> accept_new = false; /* old equals or dominates new */
>
> There's no need to make more than one test on the rows values.

I see, thanks for explaining.

Yours,
Laurenz Albe

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Guillaume Lelarge 2012-04-21 15:52:05 Re: RANGE type, and its subtype parameter
Previous Message Qi Huang 2012-04-21 06:28:52 Re: Gsoc2012 idea, tablesample