Re: multi-install PostgresNode fails with older postgres versions

> On Apr 7, 2021, at 7:37 AM, Jehan-Guillaume de Rorthais <jgdr@dalibo.com> wrote:
> 
> Hi all,
> 
> First, sorry to step in this discussion this late. I didn't noticed it before :(

Not a problem.

> I did some work about these compatibility issues in late 2020 to use
> PostgresNode in the check_pgactivity TAP tests.
> 
> See https://github.com/ioguix/check_pgactivity/tree/tests/t/lib
> 
> PostgresNode.pm, TestLib.pm, SimpleTee.pm and RecursiveCopy.pm comes unchanged
> from PostgreSQL source file (see headers and COPYRIGHT.pgsql).
> 
> Then, I'm using the facet class PostgresNodeFacet to extend it with some more
> methods. Finaly, I created one class per majpr version, each inheriting from the
> next version. That means 13 inherits from PostgresNodeFacet.pm, 12 inherits from
> 13, 11 inherits from 12, etc.
> 
> When I'm creating a new node, I'm using the "pgaTester" factory class. It
> relies on PATH to check the major version using pg_config, then loads the
> appropriate class.
> 
> That means some class overrides almost no methods but version(), which returns
> the major version. Eg.:
> https://github.com/ioguix/check_pgactivity/blob/tests/t/lib/PostgresNode12.pm
> 
> From tests, I can check the node version using this method, eg.:
> 
>  skip "skip non-compatible test on PostgreSQL 8.0 and before", 3
>    unless $node->version <= 8.0;
> 
> Of course, there's a lot of duplicate code between classes, but my main goal
> was to keep PostgresNode.pm unchanged from upstream so I can easily update it.

I see that.

> And here is a demo test file:
> https://github.com/ioguix/check_pgactivity/blob/tests/t/01-streaming_delta.t
> 
> My limited set of tests are working with versions back to 9.0 so far.
> 
> My 2¢

Hmm, I took a look.  I'm not sure that we're working on the same problem, but I might have missed something.

—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company