Re: Adding pg_dump flag for parallel export to pipes

From: Nitin Motiani <nitinmotiani(at)google(dot)com>
To: solai v <solai(dot)cdac(at)gmail(dot)com>
Cc: Hannu Krosing <hannuk(at)google(dot)com>, Mahendra Singh Thalor <mahi6run(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Adding pg_dump flag for parallel export to pipes
Date: 2026-06-09 06:34:01
Message-ID: CAH5HC94-gFS63cnQbSXZ+hDvSUNV51U+KeRU-XiY-ngu_KtJ5A@mail.gmail.com
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On Fri, May 22, 2026 at 4:04 PM solai v <solai(dot)cdac(at)gmail(dot)com> wrote:
> I then tested the patch introducing --pipe support. The feature is
> quite useful for modern workflows where users want to stream dump
> output directly to compression or upload pipelines without relying on
> intermediate storage.

Thank you for the feedback.

> gzip: dump.gz: unexpected end of file
> This suggests that concurrent writes to a shared output target are not
> coordinated and can result in invalid dumps. It would be helpful to
> clarify expected usage patterns here. For example: whether users are
> expected to generate distinct outputs per worker, or whether
> safeguards should be implemented to prevent multiple workers from
> writing to the same destination.

I added a warning for cases where the pipe command provided with
parallel dump and restore doesn't contain a `%f`. We can also add it
to the documentation. Let me know what you think.

> scenarios I observed backend logs such as:
> FATAL: connection to client lost
> Broken pipe
> While this is expected when the pipe terminates prematurely, it may be
> worth considering whether error messaging or cleanup behavior can be
> made clearer from the user perspective.

I added the failed command to the error message. I'm not sure if we
can do any auto-cleanup commands which succeeded.

Thanks & Regards

Nitin Motiani
Google

Attachment Content-Type Size
v17-0002-Add-pipe-command-support-in-pg_restore.patch application/x-patch 9.5 KB
v17-0005-Add-documentation-for-pipe-in-pg_dump-and-pg_res.patch application/x-patch 7.3 KB
v17-0003-Fixes-and-refactors-in-pipe-command.patch application/x-patch 40.4 KB
v17-0004-Add-tests-for-pipe.patch application/x-patch 22.1 KB
v17-0001-Add-pipe-command-support-for-directory-mode-of-p.patch application/x-patch 31.6 KB

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