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

Stephen Frost <sfrost(at)snowman(dot)net> writes:
> * Tom Lane (tgl(at)sss(dot)pgh(dot)pa(dot)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