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

On 2023-07-19 We 12:05, Alvaro Herrera wrote:
> 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.


Yeah, but you asked why the buildfarm didn't see this effect, and the 
answer is that it never uses version arguments like '16beta2'.


>
>>> 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.


I want to prevent things like this from happening in the future if 
someone puts a test in the development branch with  "if ($oldversion < nn)".


>
>> 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.


That seems odd. String comparison like that is supposed to work. I will 
do some tests.


>
> 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.


These comparisons only look like that. They are overloaded in 
PostgreSQL::Version.


cheers


andrew

--
Andrew Dunstan
EDB:https://www.enterprisedb.com