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From: Kirill Reshke <reshkekirill@gmail.com>
Date: Tue, 1 Apr 2025 16:14:31 +0200
Message-ID: 
 <CALdSSPgxiAaMsJoEz9c9TvE2cuoOiuRD6YAa88kmop9+37FnDw@mail.gmail.com>
Subject: Re: in BeginCopyTo make materialized view using COPY TO instead of
 COPY (query).
To: vignesh C <vignesh21@gmail.com>
Cc: jian he <jian.universality@gmail.com>,
 Fujii Masao <masao.fujii@oss.nttdata.com>,
	Andrew Dunstan <andrew@dunslane.net>,
 "David G. Johnston" <david.g.johnston@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
 Tom Lane <tgl@sss.pgh.pa.us>,
	Michael Paquier <michael@paquier.xyz>
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On Tue, 1 Apr 2025 at 15:52, vignesh C <vignesh21@gmail.com> wrote:
>
> On Tue, 1 Apr 2025 at 15:49, Kirill Reshke <reshkekirill@gmail.com> wrote:
> >
> > On Tue, 1 Apr 2025, 11:45 vignesh C, <vignesh21@gmail.com> wrote:
> >>
> >>
> >> One thing I noticed was that if the materialized view is not refreshed
> >> user will get stale data
> >>
> >> Should we document this?
> >
> > Does this patch alter thus behaviour? User will get stale data even on HEAD, why should we take a care within this thread?
>
> 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?
> This could prevent users from realizing the issue only after running
> the copy operation, which would then require them to run it again.

Yes, agree, +1 on that.

> If
> you think this is already obvious, then the note may not be necessary.

I don't think this is already obvious, but my objection is that we
should maybe discuss this as a separate issue (in a separate patch).
Looks like fixing this together with code commit is too much at once.
I prefer a one-commit-for-one-purpose style.

> Regards,
> Vignesh


-- 
Best regards,
Kirill Reshke