Re: print_path is missing GatherMerge and CustomScan support

On Thu, Jul 19, 2018 at 11:56 AM, Michael Paquier <michael(at)paquier(dot)xyz> wrote:
> On Thu, Jul 19, 2018 at 10:41:10AM +0530, Ashutosh Bapat wrote:
>> I had extensive testcases in my original patch-set to exercise that
>> code but 1. that testset was too extensive; even today
>> partition_join.sql is a separate testcase and it's quite large. 2.
>> that function returns NULL rather than throwing an error, if it can
>> not produce a parameterized path. So, unless we check whether each of
>> those paths get created no test is useful and that can only be done
>> through an EXPLAIN OUTPUT which means that the testcase becomes
>> fragile. I fine if we want to add more tests just to cover the code if
>> those are not as fragile and do not blow up partition_join too much.
>
> Did those really check the reparameterization of a MergeAppendPath for a
> child of the parent? I'd be surprised if this one was stressed as there
> was no match in the list.

I don't remember but given this evident, it was not. But there are
some testcases in partition_join which test this code using LATERAL
joins. But those do not cover the entire function.

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company