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From: David G. Johnston <[email protected]>
To: Dimitrios Apostolou <[email protected]>
Cc: [email protected]
Subject: Re: In-order pg_dump (or in-order COPY TO)
Date: Tue, 26 Aug 2025 13:31:12 -0700
Message-ID: <CAKFQuwYBVFjoNFUzsomdvRQXEEQH5A4T-+_STE=WNUomw6LZSQ@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

On Tue, Aug 26, 2025 at 12:43 PM Dimitrios Apostolou <[email protected]> wrote:

> Could the
> row-order have changed when doing COPY FROM with pg_restore?


There is no reliable, meaningful, row ordering when it comes to the
physical files.  Sure, cluster does make an attempt, but it is quite
limited in practice.


> A *logical* dump of data shouldn't be affected by on-disk order.
> Internal representation shouldn't affect the output.
>

The logical dump has no ordering - it will come out however it comes out.
"COPY <table> TO ..." doesn't have an order by clause - there is no way to
make or communicate to it that ordering is important.  For adhoc work you
can use "COPY <query> TO ..." and put and order by in the query.

David J.

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