Re: Add some tests for pg_stat_statements compatibility verification under contrib

Hi Erica,

On Wed, Mar 10, 2021 at 11:14:52AM +0800, Erica Zhang wrote:
> Hi Julien,
> Thanks a lot for the quick review. Please see my answer below in blue. Attached is the new patch.

Thanks!

>> The upgrade scripts are already tested as postgres will install 1.4 and perform
>> all upgrades to reach the default version.
> Thanks for pointing that the upgrades paths are covered by upgrade scripts tests. Since I don't need to test the upgrade, I will test the installation of different versions directly, any concern?

I think you should keep your previous approach.  The result will be the same
but it will consume less resources for that which is always good.

>> +SELECT * FROM pg_available_extensions WHERE name = 'pg_stat_statements' and installed_version = '1.4';
>> 
>> 
>> What is this supposed to test?  All those tests will break every time we change
>> the default version, which will add maintenance efforts.  It could be good to
>> have one test breaking when changing the version to remind us to add a test for
>> the new version, but not more.
> Here I just want to verify that "installed" version is the expected version. But we do have the issue as you mentioned which will add maintenance efforts. 
> 
> So I prefer to keep one test as now which can remind us to add a new version. As for others, just to check the count(*) to make sure installation is success.
> Such as SELECT count(*) FROM pg_available_extensions WHERE name = 'pg_stat_statements' and installed_version = '1.4'; What do you think?

How about tweaking your previous query so only the last execution fails when
pg_stat_statements default version is updated?  Something like:

SELECT installed_version = default_version, installed_version
FROM pg_available_extensions
WHERE name = 'pg_stat_statements';

This way the same query can be reused for both older versions and current
version.

Also, can you register your patch for the next commitfest at
https://commitfest.postgresql.org/33/, to make sure it won't be forgotten?