[YSQL] Updates fails on relation having columns with no comparator + before row trigger

[karthik-ramanathan-3006]

Jira Link: DB-12404

Description

Consider the following schema:

CREATE TABLE test (k INT PRIMARY KEY, v1 INT, v2 JSON);

CREATE OR REPLACE FUNCTION no_update() RETURNS TRIGGER
LANGUAGE PLPGSQL AS $$
BEGIN
  RAISE NOTICE 'Trigger "no_update" invoked';
  RETURN NEW;
END;
$$;

CREATE TRIGGER test_trigger BEFORE UPDATE ON test FOR EACH ROW EXECUTE FUNCTION no_update();

-- Insert a sample row
INSERT INTO test VALUES (1, 1, '{}'::json);

The following query fails:

yugabyte=# UPDATE test SET v1 = v1 + 1;
NOTICE:  00000: Trigger "no_update" invoked
ERROR:  42883: could not identify a comparison function for type json

The query fails because of the following:

• To identify the columns modified by the before row trigger, we try to compare the old and new value of each column.
• To do the comparison, we look up the comparator function for the type associated with the column.
• Column 'v2' is of type json which has no natural comparator function, causing the comparison and the query to fail.

Issue Type

kind/bug

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