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Re: In-order pg_dump (or in-order COPY TO)

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On Tue, Aug 26, 2025 at 4:31 PM David G. Johnston <david.g.johnston@xxxxxxxxx> wrote:
On Tue, Aug 26, 2025 at 12:43 PM Dimitrios Apostolou <jimis@xxxxxxx> 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.
 
Doesn't COPY TO copy out records in the order they appeared in the physical files?  That _seems_ to mean that the records laid down by COPY FROM should be in the same order as they were in the old dump files.

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