User-Agent: Cyrus-JMAP/3.5.0-alpha0-1369-gd055fb5e7c-fm-20211018.002-gd055fb5e
Mime-Version: 1.0
Message-Id: <6befff68-6293-4d75-9c66-72fe5596aa02@www.fastmail.com>
In-Reply-To: <202110191516.eufiqzha2etw@alvherre.pgsql>
References: <202110191516.eufiqzha2etw@alvherre.pgsql>
Date: Fri, 22 Oct 2021 12:20:55 -0300
From: "Euler Taveira" <euler@eulerto.com>
To: "Alvaro Herrera" <alvherre@alvh.no-ip.org>,
 "Michael Paquier" <michael@paquier.xyz>
Cc: "nikolai.berkoff" <nikolai.berkoff@pm.me>,
 "pgsql-docs@lists.postgresql.org" <pgsql-docs@lists.postgresql.org>
Subject: Re: ALTER TABLE ... SET DATA TYPE removes statistics
Content-Type: multipart/alternative;
 boundary=e249a98169d14376880e2d0394468938
Archived-At: 
 <https://www.postgresql.org/message-id/6befff68-6293-4d75-9c66-72fe5596aa02%40www.fastmail.com>
Precedence: bulk

--e249a98169d14376880e2d0394468938
Content-Type: text/plain

On Tue, Oct 19, 2021, at 12:16 PM, Alvaro Herrera wrote:
> On 2021-Oct-19, Michael Paquier wrote:
> 
> > On Mon, Oct 18, 2021 at 05:15:59PM -0300, Euler Taveira wrote:
> > > I agree that it might surprise an user and it would be good to document it.
> > > However, it does not belong to the description. I would add it to the Notes
> > > section at the end of the ALTER TABLE page.
> > 
> > No objections to the suggested addition and the location of the
> > addition (paragraph of SET DATA TYPE rather than "Notes"), but I think
> > that the phrasing could be better:
> > "The column's statistics are removed, hence a follow-up ANALYZE is
> > suited to update the statistics to the new column type."
> 
> Dunno, putting it in the middle of the existing paragraph looks odd to
> me.  I would put it in a separate one instead, as in the attached.
LGTM. I'm not sure if it is worth mentioning that the user needs to ANALYZE
only the removed column instead of the whole table. Anyway, it is good to have
statistics from the same snapshot.


--
Euler Taveira
EDB   https://www.enterprisedb.com/

--e249a98169d14376880e2d0394468938
Content-Type: text/html
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Tue, Oct 19,=
 2021, at 12:16 PM, Alvaro Herrera wrote:<br></div><blockquote type=3D"c=
ite" id=3D"qt" style=3D""><div>On 2021-Oct-19, Michael Paquier wrote:<br=
></div><div><br></div><div>&gt; On Mon, Oct 18, 2021 at 05:15:59PM -0300=
, Euler Taveira wrote:<br></div><div>&gt; &gt; I agree that it might sur=
prise an user and it would be good to document it.<br></div><div>&gt; &g=
t; However, it does not belong to the description. I would add it to the=
 Notes<br></div><div>&gt; &gt; section at the end of the ALTER TABLE pag=
e.<br></div><div>&gt;&nbsp;<br></div><div>&gt; No objections to the sugg=
ested addition and the location of the<br></div><div>&gt; addition (para=
graph of SET DATA TYPE rather than "Notes"), but I think<br></div><div>&=
gt; that the phrasing could be better:<br></div><div>&gt; "The column's =
statistics are removed, hence a follow-up ANALYZE is<br></div><div>&gt; =
suited to update the statistics to the new column type."<br></div><div><=
br></div><div>Dunno, putting it in the middle of the existing paragraph =
looks odd to<br></div><div>me.&nbsp; I would put it in a separate one in=
stead, as in the attached.<br></div></blockquote><div>LGTM. I'm not sure=
 if it is worth mentioning that the user needs to ANALYZE<br></div><div>=
only the removed column instead of the whole table. Anyway, it is good t=
o have<br></div><div>statistics from the same snapshot.<br></div><div><b=
r></div><div><br></div><div id=3D"sig112409080"><div class=3D"signature"=
>--<br></div><div class=3D"signature">Euler Taveira<br></div><div class=3D=
"signature">EDB&nbsp;&nbsp; <a href=3D"https://www.enterprisedb.com/">ht=
tps://www.enterprisedb.com/</a><br></div></div><div><br></div></body></h=
tml>
--e249a98169d14376880e2d0394468938--