Re: pgsql: Change timeline field of IDENTIFY_SYSTEM to int8 - Mailing list pgsql-committers

From Michael Paquier
Subject Re: pgsql: Change timeline field of IDENTIFY_SYSTEM to int8
Date
Msg-id YsOKgyhZRXfjts3A@paquier.xyz
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In response to Re: pgsql: Change timeline field of IDENTIFY_SYSTEM to int8  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-committers
On Mon, Jul 04, 2022 at 01:55:13AM -0400, Tom Lane wrote:
> Peter Eisentraut <peter@eisentraut.org> writes:
> > Change timeline field of IDENTIFY_SYSTEM to int8
>
> Surely this patch is far from complete?

Yeah..

> But what about whatever code is reading the output?  And what if
> that code isn't v16?  I can't believe that we can make a wire
> protocol change as summarily as this.

Assuming that one reaches a timeline of 2 billion, this change would
make the TLI consumption of the client safe to signedness.  But why is
it safe to do a protocol change when running IDENTIFY_SYSTEM?  We've
been very strict to maintain compatibility for any protocol change,
hence why should the replication protocol be treated differently?
--
Michael

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