Re: [PATCH] Add support function for containment operators

On Fri, 2023-10-13 at 14:26 +0800, jian he wrote:
> Collation problem seems solved.

I didn't review your patch in detail, there is still a problem
with my example:

CREATE TYPE textrange AS RANGE (
SUBTYPE = text,
SUBTYPE_OPCLASS = text_pattern_ops
);

CREATE TABLE tx (t text COLLATE "cs-CZ-x-icu");

INSERT INTO tx VALUES ('a'), ('c'), ('d'), ('ch');

SELECT * FROM tx WHERE t <@ textrange('a', 'd');

t
════
a
c
ch
(3 rows)

That was correct.

EXPLAIN SELECT * FROM tx WHERE t <@ textrange('a', 'd');

QUERY PLAN
════════════════════════════════════════════════════
Seq Scan on tx (cost=0.00..30.40 rows=7 width=32)
Filter: ((t >= 'a'::text) AND (t < 'd'::text))
(2 rows)

But that was weird. The operators seem wrong. Look at that
query:

SELECT * FROM tx WHERE t >= 'a' AND t < 'd';

t
═══
a
c
(2 rows)

But the execution plan is identical...

I am not sure what is the problem here, but in my opinion the
operators shown in the execution plan should be like this:

SELECT * FROM tx WHERE t ~>=~ 'a' AND t ~<~ 'd';

t
════
a
c
ch
(3 rows)

Yours,
Laurenz Albe