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Date: Thu, 7 Nov 2024 08:37:35 -0800
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Subject: Re: About the stability of COPY BINARY data
To: Dominique Devienne <ddevienne@gmail.com>, pgsql-general@postgresql.org
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From: Adrian Klaver <adrian.klaver@aklaver.com>
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On 11/6/24 08:20, Dominique Devienne wrote:
>>>From https://www.postgresql.org/docs/current/sql-copy.html:
> |> binary-format file is less portable across machine architectures
> and PostgreSQL versions
> 
> In my experience, the binary encoding of binding/resultset/copy is
> endian neutral (network byte order), so what is the less portable
> across machine architectures that warning about?
> 
> Also, does the code for per-type _send() and _recv() functions really change
> across versions of PostgreSQL? How common are instances of such
> changes across versions? Any examples of such backward-incompatible
> changes, in the past?
> 
> The binary data contains OIDs, but if sticking to built-in types,
> which OIDs are unlikely to change across versions?
> 
> I'm obviously storing COPY BINARY data (we have lots of bytea
> columns), and I wonder how bad it is long term, and across PostgreSQL
> versions.

If I where to hazard a guess this plays a part:

https://www.postgresql.org/docs/current/sql-copy.html

"To determine the appropriate binary format for the actual tuple data 
you should consult the PostgreSQL source, in particular the *send and 
*recv functions for each column's data type (typically these functions 
are found in the src/backend/utils/adt/ directory of the source 
distribution)."

> 
> Thanks for any insights, --DD
> 
> 

-- 
Adrian Klaver
adrian.klaver@aklaver.com