This bug seems to have slipped off the radar screen, but it's still a bug. I continue to believe that the best fix is to disallow SRFs in window definitions, and present the trivial patch to do so.
This patch fixes the original issue reported by Daniel. Another issue discussed in this thread is the weirdness when there are SRFs in the targetlist of a query with DISTINCT ON clause, as described by David.
create table ab (a int, b int); insert into ab values(1,1),(1,2),(2,1),(2,2);
# select distinct on (a) a, b, generate_series(1,2) g from ab order by a, b; a | b | g ---+---+--- 1 | 1 | 1 1 | 1 | 2 2 | 1 | 1 2 | 1 | 2 (4 rows)
# select distinct on (a) a, b, g from ab, lateral generate_series(1,2) as g order by a, b; a | b | g ---+---+--- 1 | 1 | 1 2 | 1 | 1 (2 rows)
According to the doc these two queries are supposed to be 'almost exactly the same'. So it's weird to see they give different number of output rows.
Should we also fix this issue? If so it seems we need some changes about postponing SRFs in make_sort_input_target().
