On 4/7/21 10:37 AM, Jehan-Guillaume de Rorthais wrote: > Hi all, > > First, sorry to step in this discussion this late. I didn't noticed it before > :( > > 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. > > 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 2ยข
I don't really want to create a multitude of classes. I think Mark is basically on the right track. I started off using a subclass of PostgresNode but was persuaded not to go down that route, and instead we have made some fairly minimal changes to PostgresNode itself. I think that was a good decision. If you take out the versioning subroutines, the actual version-aware changes Mark is proposing to PostgresNode are quite small - less that 200 lines supporting versions all the way back to 8.1. That's pretty awesome. cheers andrew -- Andrew Dunstan EDB: https://www.enterprisedb.com
