Re: [PATCH] Add support function for containment operators

> On Sat, 2023-04-29 at 17:07 +0200, Kim Johan Andersson wrote:
> > I had noticed that performance wasn't great when using the @> or <@
> > operators when examining if an element is contained in a range.
> > Based on the discussion in [1] I would like to suggest the following
> > changes:
> >
> > This patch attempts to improve the row estimation, as well as opening
> > the possibility of using a btree index scan when using the containment
> > operators.

I managed to break the patch:

CREATE DATABASE czech ICU_LOCALE "cs-CZ" LOCALE "cs_CZ.utf8" TEMPLATE template0;

\c czech

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

CREATE TABLE tx (t text);

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

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)

SELECT * FROM tx WHERE t <@ textrange('a', 'd');
ERROR: could not determine which collation to use for string comparison
HINT: Use the COLLATE clause to set the collation explicitly.

The replacement operators are wrong; it should be ~>=~ and ~<~ .

Also, there should be no error message.
The result should be 'a', 'c' and 'ch'.

Yours,
Laurenz Albe