MIME-Version: 1.0
References: 
 <CACJufxHVxnyRYy67hiPePNCPwVBMzhTQ6FaL9_Te5On9udG=yg@mail.gmail.com>
 <Z2Sz7LU1akdewn5U@paquier.xyz>
 <CACJufxGvy6QNMwZ5xd=L31F+4Rr6aXCASeMFyLZS+TVssK5+vA@mail.gmail.com>
 <CACJufxGZgh4oNV_8TqBwRoL+WFB2n3EqN97aMcuEmjuG+qm0qw@mail.gmail.com>
 <CACJufxHnyH4Zv+RtOABn8-1PjxkKch9R58dGhr+hCnV0LmNxSQ@mail.gmail.com>
 <CALdSSPgsgC_CGDjTyzu=1FAbuavTRsGFDnnm7ufGuWcd29QUHQ@mail.gmail.com>
 <CACJufxE35HxSMqG6su0txZwOLpbnBsDBav5eigxt6L8Nk8bJwQ@mail.gmail.com>
 <CALdSSPi3Gb=fi0ZCoJhAp3HQYKJmiCShcX4xMcUBSL0s5byBXQ@mail.gmail.com>
 <CAKFQuwbs61rxxCUVhECLSq4Xrz9s54dD2TzhX58d7+6WcC8dpA@mail.gmail.com>
 <e38cbf42-0f8e-4c3b-8c77-70c83116fdb2@dunslane.net>
 <CAKFQuwbD775kSHFfyF3shu+XMTX=3SEH+_JYLOWvrPo3y5dK-w@mail.gmail.com>
 <442e62f7-ef64-4df1-8453-d682fe9bdaa3@dunslane.net>
 <CAKFQuwaMFiNGhk-F+TG4uVjiAfFwar6t+7fUc0mKDz55DGODcw@mail.gmail.com>
 <425ebe4b-06c5-4212-af68-fd0e5537c250@dunslane.net>
 <f6abc172-f300-4e90-bcc6-c189d29d2f9f@oss.nttdata.com>
 <CACJufxF3noNs9O6O3fL783h2-Sy1wfJb=0H+WMFmOLuhkfJw8w@mail.gmail.com>
 <CALDaNm3_oLZK=L6Si3JXDh7fL+NurF07CHtABPkhFOZ9xmsYZg@mail.gmail.com>
 <CALdSSPiNtJMQFhSWSJnkwqwTkDAe3nqTjZ2yqs9jZVC6SYh6FA@mail.gmail.com>
 <CALDaNm2OCk8kg6jeswYfCYTieAiO1RHe-D0ZxfL0XCV4dQ4YPA@mail.gmail.com>
In-Reply-To: 
 <CALDaNm2OCk8kg6jeswYfCYTieAiO1RHe-D0ZxfL0XCV4dQ4YPA@mail.gmail.com>
From: "David G. Johnston" <david.g.johnston@gmail.com>
Date: Tue, 1 Apr 2025 07:27:24 -0700
Message-ID: 
 <CAKFQuwZQFhkOR4VAZoH_Hd0OhCJx-mHW4dRFk1R7phjemvjbbg@mail.gmail.com>
Subject: Re: in BeginCopyTo make materialized view using COPY TO instead of
 COPY (query).
To: vignesh C <vignesh21@gmail.com>
Cc: Kirill Reshke <reshkekirill@gmail.com>,
 jian he <jian.universality@gmail.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
 Andrew Dunstan <andrew@dunslane.net>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
 Tom Lane <tgl@sss.pgh.pa.us>,
	Michael Paquier <michael@paquier.xyz>
Content-Type: multipart/alternative; boundary="0000000000001040880631b8587e"
Archived-At: 
 <https://www.postgresql.org/message-id/CAKFQuwZQFhkOR4VAZoH_Hd0OhCJx-mHW4dRFk1R7phjemvjbbg%40mail.gmail.com>
Precedence: bulk

--0000000000001040880631b8587e
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Tue, Apr 1, 2025 at 6:52=E2=80=AFAM vignesh C <vignesh21@gmail.com> wrot=
e:

>
> We are not changing the existing behavior. However, since copying data
> from large tables can take a significant amount of time, would it be
> helpful to add a cautionary note advising users to refresh the
> materialized view before running copy command to avoid stale data?
>
>
No, for the same reason the caveat about WITH NO DATA need not be mentioned
either.  These are the inherent properties/trade-offs of using a
materialized view versus a normal view.  They are discussed when talking
about the creation and usage of materialized views specifically.  Features
that interact with materialized views consistent with these two documented
properties do not need to point out that fact. i.e., the existing
non-documenting of those two points in SELECT is appropriate, and should be
emulated in COPY.  The output doesn't change if you write "copy table"
instead of "copy (select * from table)" so nothing needs to be pointed out.

David J.

--0000000000001040880631b8587e
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div dir=3D"ltr"><div class=3D"gmail_default" style=3D"fon=
t-family:arial,helvetica,sans-serif"><span style=3D"font-family:Arial,Helve=
tica,sans-serif">On Tue, Apr 1, 2025 at 6:52=E2=80=AFAM vignesh C &lt;<a hr=
ef=3D"mailto:vignesh21@gmail.com">vignesh21@gmail.com</a>&gt; wrote:</span>=
</div></div><div class=3D"gmail_quote gmail_quote_container"><blockquote cl=
ass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid=
 rgb(204,204,204);padding-left:1ex"><br>
We are not changing the existing behavior. However, since copying data<br>
from large tables can take a significant amount of time, would it be<br>
helpful to add a cautionary note advising users to refresh the<br>
materialized view before running copy command to avoid stale data?<br>
<br></blockquote><div><br></div><div class=3D"gmail_default" style=3D"font-=
family:arial,helvetica,sans-serif">No, for the same reason the caveat about=
 WITH NO DATA need not be mentioned either.=C2=A0 These are the inherent pr=
operties/trade-offs of using a materialized view versus a normal view.=C2=
=A0 They are discussed when talking about the creation and usage of materia=
lized views specifically.=C2=A0 Features that interact with materialized vi=
ews consistent with these two documented properties do not need to point ou=
t that fact. i.e., the existing non-documenting of those two points in SELE=
CT is appropriate, and should be emulated in COPY.=C2=A0 The output doesn&#=
39;t change if you write &quot;copy table&quot; instead of &quot;copy (sele=
ct * from table)&quot; so nothing needs to be pointed out.</div><div class=
=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-serif"><br></d=
iv><div class=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-s=
erif">David J.</div><div class=3D"gmail_default" style=3D"font-family:arial=
,helvetica,sans-serif"><br></div></div></div>

--0000000000001040880631b8587e--