Re: [COMMITTERS] pgsql: Further fixes for degenerate outer join clauses.

Stephen Frost <sfrost@snowman.net> writes:
> * Tom Lane (tgl@sss.pgh.pa.us) wrote:
>> I'm not entirely sure what to do about this.  We could back-patch that
>> patch into 9.0 and 9.1, but it's conceivable somebody would squawk about
>> planner behavioral changes.  The only other idea that seems practical is
>> to remove regression test cases that have platform-specific results in
>> those branches.  Probably that wouldn't result in a real reduction in the
>> quality of the test coverage for those branches (we could still execute
>> the query, just not EXPLAIN it).  But it seems like a pretty ad-hoc
>> answer, and the next case might be one that hurts more not to test.
>> 
>> Thoughts?

> Have an alternate file for those other cases, rather than remove the
> test?  The complaint was about one buildfarm member, so hopefully that's
> practical and doesn't require a lot of different permutations.

I considered that but don't find it practical or attractive, especially
not if the only way to keep such a file updated is to wait and see whether
the buildfarm complains.

On the whole I'm leaning towards back-patching 33e99153e.  While the case
of exactly equal plan costs does come up in the regression tests (which
tend to inspect plans for queries on small simple tables), I think it's
relatively unlikely to happen with real-world data.        regards, tom lane