Hello
With the latest version, an XX000 cache lookup can surface to the user
with two columns with different collations:
Minimal repro:
CREATE EXTENSION IF NOT EXISTS pg_trgm;
DROP TABLE IF EXISTS ic_a, ic_b;
CREATE TABLE ic_a(x text COLLATE "C");
CREATE TABLE ic_b(y text COLLATE "POSIX");
INSERT INTO ic_a VALUES ('hello world');
INSERT INTO ic_b VALUES ('hello word');
SELECT similarity(x, y) FROM ic_a, ic_b;
-- ERROR: XX000: cache lookup failed for collation 0