Thread

1. Re: SLOPE - Planner optimizations on monotonic expressions.

   Alexandre Felipe <o.alexandre.felipe@gmail.com> — 2026-05-07T19:12:25Z

   On Wed, Mar 25, 2026 at 5:18 AM Corey Huinker <corey.huinker@gmail.com>
   wrote:
   > 0002 is missing the catversion bump but that's fine at this early stage.
   
   postponing catversion bump for a time when we get closer to commit,
   v8 doesn't include catversion.h changes, hoping to require less frequent
   rebases.
   

2. Re: SLOPE - Planner optimizations on monotonic expressions.

   Zsolt Parragi <zsolt.parragi@percona.com> — 2026-05-08T22:18:55Z

   > There were too many possibilities for my brain to enumerate, so I scripted
   > the
   > extraction and presentation of that in regress/sql/slope.sql in commit 0005.
   
   Apologies, I forgot to reply to this earlier, the new NULL handling
   looks good. Nice test!
   
   I found one more corner case with infinities (same applies also with
   negative infinity):
   
   CREATE TABLE t8 (x float8);
   INSERT INTO t8 VALUES (-2), (-1), (0), (1), (2);
   CREATE INDEX t8_x_idx ON t8 (x);
   ANALYZE t8;
   
   SET enable_seqscan = off;
   SELECT x, x * 'Infinity'::float8 AS f FROM t8 ORDER BY x * 'Infinity'::float8;
   
   SET enable_indexscan = off;
   SET enable_indexonlyscan = off;
   SET enable_seqscan = on;
   SELECT x, x * 'Infinity'::float8 AS f FROM t8 ORDER BY x * 'Infinity'::float8;
   
   
   
   

3. Re: SLOPE - Planner optimizations on monotonic expressions.

   Alexandre Felipe <o.alexandre.felipe@gmail.com> — 2026-05-10T15:53:49Z

   On Fri, May 8, 2026 at 11:19 PM Zsolt Parragi <zsolt.parragi@percona.com>
   wrote:
   
   > I found one more corner case with infinities (same applies also with
   > negative infinity):
   >
   
   This will restrict a lot of cases.
   
   
   slope_corner_cases.sql enumerate experssions and orders producing
   permutations of (-inf, -1, 0, 1, +inf, nan) mapped to (1,2,3,4,5,6)
   to visualize other similar corner cases.
   
   Apparently the violations boil down to two cases
   * All basic arithmetic operations with infinity constant (with a lucky
   exception x - inf)
   * Every decreasing function where the index key.
   e.g. `-x desc` would have NaNs first
   
   Should I simply detect and disable the above cases?
   
   sqrt(x < 0) already raise an exception, is it safe to assume that for all
   the limited domain functions?