On Sun, Jul 31, 2022 at 12:07 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
I took a quick look through this. The executor changes are indeed impressively short, but that's largely because you've paid zero attention to updating obsoleted comments. For example, in nodeHashjoin.c there are lots of references to right/full joins that likely now need to cover right-anti. I'm not sure that the empty-rel startup optimizations are correct for this case, either.
Thanks for the review! Yeah, you're right. I neglected to update the related comments. Will do that in the new patch. For the empty-rel startup optimizations, since the right-anti join also does null-fill on inner relation (the HJ_FILL_INNER case), I think we cannot skip building the hash table even when the outer rel is completely empty.
Here is the new patch which addresses the obsoleted comments.
