pg.ddx.io  pgsql-bugs@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Junwang Zhao <zhjwpku@gmail.com>
Cc: rekgrpth@gmail.com
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18247: Integer overflow leads to negative width
Date: Tue, 19 Dec 2023 10:22:20 -0500
Message-ID: <36777.1702999340@sss.pgh.pa.us> (raw)
In-Reply-To: <CAMbWs4-pYv=UkkdF_47w-a5OSgs5GQaZANib0YJc6mSp531Z5A@mail.gmail.com>
References: <18247-11ac477f02954422@postgresql.org>
	<CAMbWs48nZf9XgAVpXbOnwGWWLnmoOZb51wnhkNW5xfz_PyOyCw@mail.gmail.com>
	<2781181.1702565025@sss.pgh.pa.us>
	<CAMbWs4_8+mtt5C8EXmfHa_Hs-OW6EhEz_XjhzBk8miwg2h65CQ@mail.gmail.com>
	<2993260.1702654983@sss.pgh.pa.us>
	<CAMbWs49A6rMO6WD1ECvZUKXuzMxBDyXP6CmJKQoCS5=w-tjL7w@mail.gmail.com>
	<CAEG8a3+=_hWJgGVzWBNrOQtuSsYFOzu4esnQ=G+XfqAeRykQKw@mail.gmail.com>
	<4099430.1702933230@sss.pgh.pa.us>
	<CAMbWs48NGPnJiqkRZx7RCYhyjK_JP0qkxVVjrD84FDYZbD4yqw@mail.gmail.com>
	<4150261.1702958937@sss.pgh.pa.us>
	<CAMbWs4-pYv=UkkdF_47w-a5OSgs5GQaZANib0YJc6mSp531Z5A@mail.gmail.com>

Richard Guo <guofenglinux@gmail.com> writes:
> On Tue, Dec 19, 2023 at 12:08 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Thanks for looking!  Do you have an opinion about the int64-vs-double
>> question?

> To be honest, I don't have a preference on which one is better.  I think
> double is good enough for now as we don't need to worry about overflow
> with it.

After sleeping on it, I'm coming around to the idea that int64 will
be better.  The argument that convinces me is that using int64
provides a datatype-based clue that we are working with a width
and not a row count, cost, or selectivity number.  I don't feel
a need to go as far as invent a typedef alias like Cardinality;
but plain "double" in the planner tends to be a rowcount estimate,
which is not what we want people to think of.

I'll make that change and push it.

BTW, I think it's sufficient to fix this in HEAD.  The troublesome
example seems quite artificial to me, and we've not heard field
reports suggesting that people have had real problems here.

			regards, tom lane





view thread (21+ messages)  latest in thread

Message-ID: <36777.1702999340@sss.pgh.pa.us>
Permalink:  ../36777.1702999340@sss.pgh.pa.us/
Also on:    postgresql.org/message-id/36777.1702999340@sss.pgh.pa.us

 · 

reply
Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-bugs@postgresql.org
  Cc: tgl@sss.pgh.pa.us, guofenglinux@gmail.com, zhjwpku@gmail.com, rekgrpth@gmail.com, pgsql-bugs@lists.postgresql.org
  Subject: Re: BUG #18247: Integer overflow leads to negative width
  In-Reply-To: <36777.1702999340@sss.pgh.pa.us>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox