Re: Extracting cross-version-upgrade knowledge from buildfarm client

On 2023-Jul-19, Andrew Dunstan wrote:

>
> On 2023-07-19 We 07:05, Alvaro Herrera wrote:
> > I just hit a snag testing this. It turns out that the
> > PostgreSQL::Version comparison stuff believes that 16beta2 < 16, which
> > sounds reasonable. However, because of that, the AdjustUpgrade.pm
> > stanza that tries to drop tables public.gtest_normal_child{2} in
> > versions earlier than 16 fails, because by 16 these tables are dropped
> > in the test itself rather than left to linger, as was the case in
> > versions 15 and earlier.

> The buildfarm module assumes that no adjustments are necessary if the old
> and new versions are the same (e.g. HEAD to HEAD). And it never passes in a
> version like '16beta2'. It extracts the version number from the branch name,
> e.g. REL_16_STABLE => 16.

Hmm, OK, but I'm not testing the same versions -- I'm testing 16beta2 to
17devel.

> > I can fix this either by using DROP IF EXISTS in that stanza, or by
> > making AdjustUpgrade use 'version <= 15'. Any opinions on which to
> > prefer?
>
> The trouble is this could well break the next time someone puts in a test
> like this.

Hmm, I don't understand what you mean.

> Maybe we need to make AdjustUpgrade just look at the major version,
> something like:
>
>    $old_version = PostgreSQL::Version->new($old_version->major);

It seems like that does work, but if we do that, then we also need to
change this line:

if ($old_version lt '9.5')
to
if ($old_version < '9.5')

otherwise you get some really mysterious failures about trying to drop
public.=>, which is in fact no longer accepted syntax since 9.5; and the
stringwise comparison returns the wrong value here.

TBH I'm getting a sense of discomfort with the idea of having developed
a Postgres-version-number Perl module, and in the only place where we
can use it, have to settle for numeric comparison instead.

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
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