Based on this article ( http://thenoyes.com/littlenoise/?p=167 ) I was trying to make the same in Pg to see the effects (pg 9.1.1). I found this: postgres=# explain(buffers true, costs true, analyze true ) select i from random_values; QUERY PLAN -------------------------------------------------------------------------------------------------------------------------- Seq Scan on random_values (cost=0.00..16897.00 rows=1000000 width=4) (actual time=0.362..2804.651 rows=1000000 loops=1) Buffers: shared hit=576 read=6321 Total runtime: 5340.656 ms (3 rows) Time: 5342.060 ms postgres=# explain (buffers true, costs true, analyze true ) (select i from random_values) UNION ALL (SELECT NULL LIMIT 0); QUERY PLAN -------------------------------------------------------------------------------------------------------------------------------------- Result (cost=0.00..16897.02 rows=1000001 width=4) (actual time=0.203..13160.797 rows=1000000 loops=1) Buffers: shared hit=608 read=6289 -> Append (cost=0.00..16897.02 rows=1000001 width=4) (actual time=0.196..7925.918 rows=1000000 loops=1) Buffers: shared hit=608 read=6289 -> Seq Scan on random_values (cost=0.00..16897.00 rows=1000000 width=4) (actual time=0.190..2852.144 rows=1000000 loops=1) Buffers: shared hit=608 read=6289 -> Limit (cost=0.00..0.01 rows=1 width=0) (actual time=0.007..0.007 rows=0 loops=1) -> Result (cost=0.00..0.01 rows=1 width=0) (never executed) Total runtime: 15680.066 ms (9 rows) Time: 15681.999 ms 10 seconds to UNION *nothing*? Is an expected behavior? -- -- Emanuel Calvo Helpame.com -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
