Re: Trouble Upgrading Postgres

Adrian Klaver wrote:

> > So there's no way it can deal with the contents over 500MB, and the
> > ones just under that limit may also be problematic.
>
> To me that looks like a bug, putting data into a record you cannot get out.

Strictly speaking, it could probably get out with COPY in binary format,
but pg_dump doesn't use that.

It's undoubtedly very annoying that a database can end up with
non-pg_dump'able contents, but it's not an easy problem to solve.
Some time ago, work was done to extend the 1GB limit
but eventually it got scratched. The thread in [1] discusses
many details of the problem and why the proposed solution
were mostly a band aid. Basically, the specs of COPY
and other internal aspects of Postgres are from the 32-bit era when
putting the size of an entire CDROM in a single row/column was not
anticipated as a valid use case.
It's still a narrow use case today and applications that need to store
big pieces of data like that should slice them in chunks, a bit like in
pg_largeobject, except in much larger chunks, like 1MB.

[1] pg_dump / copy bugs with "big lines" ?
https://www.postgresql.org/message-id/1836813.YmyOrS99PX%40ronan.dunklau.fr

Best regards,
--
Daniel Vérité
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