Heikki Linnakangas <hlinnaka@iki.fi> writes: > On 22/12/2023 17:24, Tom Lane wrote: >> How much of your patchset still makes sense if we assume that we >> can always extract the ORDER BY column values from the index?
> That would make it much less interesting. But I don't think that's a > good assumption. Especially in the kNN case, the ORDER BY value would > not be stored in the index. Most likely the index needs to calculate it > in some form, but it might take shortcuts like avoiding the sqrt().
Yeah, fair point. I'll try to take a look at your patchset after the holidays.
Agreed.
I haven't looked into these patches, but it seems that there is an issue with how the targetlist is handled for foreign rels. The following test case for postgres_fdw hits the Assert in apply_tlist_labeling().
contrib_regression=# SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; server closed the connection unexpectedly
When we create foreign final path in add_foreign_final_paths(), we use root->upper_targets[UPPERREL_FINAL] as the PathTarget. This PathTarget is set in grouping_planner(), without removing the junk columns. I think this is why the above query hits the Assert.
