Postgres 17

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select version();

version

PostgreSQL 17.2 (Debian 17.2-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit

SELECT 1

CREATE COLLATION collat_ci (
  provider = 'icu',
  locale = 'und-u-ks-level2',
  deterministic = false
);

CREATE COLLATION

CREATE TABLE foo(bar text COLLATE collat_ci);

CREATE TABLE

INSERT INTO foo(bar) VALUES('TestTSsds');

INSERT 0 1

SELECT * FROM foo WHERE UPPER(bar) COLLATE "default" LIKE UPPER('%test%');

bar

TestTSsds

SELECT 1