On Tue, Mar 2, 2021, at 19:17, Mark Dilger wrote: > > On Mar 2, 2021, at 10:08 AM, Joel Jacobson <j...@compiler.org> wrote: > > That's why the patch doesn't change equality. > > How does that work if I SELECT DISTINCT ON (nr) ... and then take upper(nr). > It's just random which values I get?
Yes. It's random, since equality isn't changed, the sort operation cannot tell the difference, and nor could a user who isn't aware of upper() / lower() could reveal differences. Demo: CREATE TABLE t AS SELECT int4range(i,i+FLOOR(random()*2)::integer,'[)') AS nr FROM generate_series(1,10) AS i; SELECT nr, lower(nr), upper(nr) FROM t ORDER BY 1; nr | lower | upper --------+-------+------- empty | 10 | 10 empty | 4 | 4 empty | 6 | 6 empty | 7 | 7 empty | 1 | 1 empty | 3 | 3 [2,3) | 2 | 3 [5,6) | 5 | 6 [8,9) | 8 | 9 [9,10) | 9 | 10 (10 rows) SELECT DISTINCT ON (nr) nr, lower(nr), upper(nr) FROM t ORDER BY 1; nr | lower | upper --------+-------+------- empty | 10 | 10 [2,3) | 2 | 3 [5,6) | 5 | 6 [8,9) | 8 | 9 [9,10) | 9 | 10 (5 rows) /Joel
