PostgreSQL procedure to update large table in batches

update_table_in_batches.sql

-- usage:
-- CALL update_table_in_batches('table_1', array['a = 1'], batch_size := 10);
-- CALL update_table_in_batches('table_2', array['b = 2'], track_by := 'created', initial_value := '2021-01-01'::timestamp);

CREATE OR REPLACE PROCEDURE update_table_in_batches(
    target_table text,
    set_expressions text[],
    track_by text default 'id',
    initial_value anyelement default 0,
    batch_size integer default 1000,
    __last_value anyelement default null
) AS $body$
DECLARE
    updated_count integer;
    start_time timestamptz := clock_timestamp();
BEGIN
    LOOP
        SELECT initial_value INTO __last_value;

        EXECUTE format($$
            WITH updated_rows AS (
                UPDATE %1$I
                SET $$ || array_to_string(set_expressions, ',') || $$
                WHERE %2$I IN (
                    SELECT %2$I
                    FROM %1$I
                    WHERE %2$I > %3$L
                    LIMIT %4$L
                )
                RETURNING %2$I
            )
            SELECT count(%2$I), max(%2$I) FROM updated_rows
        $$, target_table, track_by, initial_value, batch_size)
        INTO updated_count, initial_value;

        COMMIT;

        IF updated_count > 0 AND initial_value = __last_value THEN
            RAISE EXCEPTION 'Cycle detected: some rows (%) were updated, but the tracked value has not changed (%). Try to increase the batch_size.',
                updated_count,
                initial_value;
        END IF;

        IF updated_count = 0 THEN
            EXIT;
        END IF;

        RAISE NOTICE 'Last value: %, updated: %, time spent: %',
            initial_value,
            updated_count,
            clock_timestamp() - start_time;

    END LOOP;
END
$body$ LANGUAGE plpgsql;