test=# EXPLAIN ANALYZE
test-# SELECT device_name FROM routers
test-# WHERE routing_protocol = 'is-is'
test-# UNION ALL
test-# SELECT device_name FROM routers
test-# WHERE routing_protocol = 'ripv2';
                                                QUERY PLAN                                                
----------------------------------------------------------------------------------------------------------
 Append  (cost=0.00..9.95 rows=113 width=11) (actual time=0.204..1.863 rows=113 loops=1)
   ->  Seq Scan on routers  (cost=0.00..4.41 rows=30 width=11) (actual time=0.201..0.836 rows=30 loops=1)
         Filter: ((routing_protocol)::text = 'is-is'::text)
   ->  Seq Scan on routers  (cost=0.00..4.41 rows=83 width=11) (actual time=0.385..0.904 rows=83 loops=1)
         Filter: ((routing_protocol)::text = 'ripv2'::text)
 Total runtime: 2.109 ms
(6 rows)