On Mon, Sep 25, 2023 at 3:11 PM Richard Guo <guofengli...@gmail.com> wrote:
> I think the root cause is that when we generate distinct_pathkeys, we > failed to realize that Var 'b' might be nullable by the grouping sets, > so it's no longer always equal to Var 'a'. It's not correct to deem > that the PathKey for 'b' is redundant and thus remove it from the > pathkeys list. > > We have the same issue when generating sort_pathkeys. As a result, we > may have the final output in the wrong order. There were several > reports about this issue before, such as [1][2]. > > To fix this issue, I'm thinking that we mark the grouping expressions > nullable by grouping sets with a dummy RTE for grouping sets, something > like attached. > Hi Tom, I'm wondering if you've got a chance to look into this issue. What do you think about the fix? Thanks Richard
