first_last_agg

pig build pkg first_last_agg;		# build rpm

pig repo add pgsql -u   # add both repo and update cache

pig install first_last_agg;		# install via package name, for the active PG version

pig install first_last_agg -v 18;   # install for PG 18
pig install first_last_agg -v 17;   # install for PG 17
pig install first_last_agg -v 16;   # install for PG 16
pig install first_last_agg -v 15;   # install for PG 15
pig install first_last_agg -v 14;   # install for PG 14

CREATE EXTENSION first_last_agg;

CREATE EXTENSION first_last_agg;

-- Get the first and last values (use ORDER BY for deterministic results)
SELECT id, first(val ORDER BY ts), last(val ORDER BY ts)
FROM events
GROUP BY id;

-- Without ORDER BY, the ordering within groups is undefined
SELECT department, first(salary ORDER BY hire_date)
FROM employees
GROUP BY department;