Re: Why does create_gather_merge_plan need make_sort?

On 11/20/20 11:24 PM, James Coleman wrote:
> While looking at another issue I noticed that create_gather_merge_plan
> calls make_sort if the subplan isn't sufficiently sorted. In all of
> the cases I've seen where a gather merge path (not plan) is created
> the input path is expected to be properly sorted, so I was wondering
> if anyone happened to know what case is being handled by the make_sort
> call. Removing it doesn't seem to break any tests.
> 

Yeah, I think you're right this is dead code, essentially. We're only
ever calling create_gather_merge_path() with pathkeys matching the
subpath. And it's like that on REL_12_STABLE too, i.e. before the
incremental sort was introduced.


regards

-- 
Tomas Vondra
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