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From: "David G. Johnston" <david.g.johnston@gmail.com>
Date: Sun, 29 Mar 2026 20:20:20 -0700
Message-ID: 
 <CAKFQuwYtdN4chM2HzcNsOJMvsVqE2LnKGTvndNeGW8s66g0Acg@mail.gmail.com>
Subject: Re: docs: warn about post-data-only schema dumps with parallel
 restore.
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: vaibhave postgres <postgresvaibhave@gmail.com>,
 pgsql-hackers@postgresql.org
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On Sun, Mar 29, 2026 at 11:33=E2=80=AFAM Tom Lane <tgl@sss.pgh.pa.us> wrote=
:

> "David G. Johnston" <david.g.johnston@gmail.com> writes:
> > On Sun, Jan 25, 2026 at 10:23=E2=80=AFPM vaibhave postgres <
> > postgresvaibhave@gmail.com> wrote:
> >> Following up on the discussion in [1] about pg_restore failing to
> restore
> >> post-data items due to circular foreign key deadlocks.
> >> I=E2=80=99m attaching a doc patch that adds a warning about using post=
-data-only
> >> schema dumps together with parallel restore.
>
> > Not a fan of the patch overall though.  I'd want to add something to
> > pg_restore noting that use of --jobs for constraint restoration needs
> > schema information to compute the restoration order.
>
> Yeah, dropping this into the list of options is bad.  We put caveats
> like that into the Notes section usually.
>
> I also tend to think that it'd be better to document this under
> pg_restore: when people run into this type of failure, they are going
> to go to the pg_restore docs not the pg_dump docs to understand it.
> I guess there could be a case for repeating the info in both the
> pg_dump and pg_restore pages, but that feels a bit verbose.
>
> So maybe like the attached?
>
>
Works for me.

But how about adding something like the following to the pg_dump notes?  We
already have the corresponding link going to pg_dump in the pg_restore
notes.

"If producing a non-plaint-text format output see also the pg_restore
documentation for details on how the restore process uses the different
sections."

David J.

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<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 Sun, Mar 29, 2026 at 11:33=E2=80=AFAM Tom Lane &lt;<a h=
ref=3D"mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt; wrote:</span></d=
iv></div><div class=3D"gmail_quote gmail_quote_container"><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
b(204,204,204);padding-left:1ex">&quot;David G. Johnston&quot; &lt;<a href=
=3D"mailto:david.g.johnston@gmail.com" target=3D"_blank">david.g.johnston@g=
mail.com</a>&gt; writes:<br>
&gt; On Sun, Jan 25, 2026 at 10:23=E2=80=AFPM vaibhave postgres &lt;<br>
&gt; <a href=3D"mailto:postgresvaibhave@gmail.com" target=3D"_blank">postgr=
esvaibhave@gmail.com</a>&gt; wrote:<br>
&gt;&gt; Following up on the discussion in [1] about pg_restore failing to =
restore<br>
&gt;&gt; post-data items due to circular foreign key deadlocks.<br>
&gt;&gt; I=E2=80=99m attaching a doc patch that adds a warning about using =
post-data-only<br>
&gt;&gt; schema dumps together with parallel restore.<br>
<br>
&gt; Not a fan of the patch overall though.=C2=A0 I&#39;d want to add somet=
hing to<br>
&gt; pg_restore noting that use of --jobs for constraint restoration needs<=
br>
&gt; schema information to compute the restoration order.<br>
<br>
Yeah, dropping this into the list of options is bad.=C2=A0 We put caveats<b=
r>
like that into the Notes section usually.<br>
<br>
I also tend to think that it&#39;d be better to document this under<br>
pg_restore: when people run into this type of failure, they are going<br>
to go to the pg_restore docs not the pg_dump docs to understand it.<br>
I guess there could be a case for repeating the info in both the<br>
pg_dump and pg_restore pages, but that feels a bit verbose.<br>
<br>
So maybe like the attached?<br><br></blockquote><div><br></div><div><div cl=
ass=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-serif">Work=
s for me.</div><br></div><div class=3D"gmail_default" style=3D"font-family:=
arial,helvetica,sans-serif">But how about adding something like the followi=
ng to the pg_dump notes?=C2=A0 We already have the corresponding link going=
 to pg_dump in the pg_restore notes.</div><div class=3D"gmail_default" styl=
e=3D"font-family:arial,helvetica,sans-serif"><br></div><div class=3D"gmail_=
default" style=3D"font-family:arial,helvetica,sans-serif">&quot;If producin=
g a non-plaint-text format output see also the pg_restore documentation for=
 details on how the restore process uses the different sections.&quot;</div=
><div class=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-ser=
if"><br></div><div class=3D"gmail_default" style=3D"font-family:arial,helve=
tica,sans-serif">David J.</div><div class=3D"gmail_default" style=3D"font-f=
amily:arial,helvetica,sans-serif"><br></div></div></div>

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