Re: Why hash join instead of nested loop?

On Mon, 2005-08-08 at 20:58, Tom Lane wrote:
> I'd be interested to see results from other people using 7.4.* too.

7.4.8:

QUERY
PLAN
----------------------------------------------------------------------------------------------------------------------------------------------------
Hash Join (cost=4.83..5.91 rows=1 width=14) (actual time=0.122..0.126
rows=1 loops=1)
Hash Cond: ("outer".id = "inner".obj2)
-> Seq Scan on rtmessagestate (cost=0.00..1.05 rows=5 width=14)
(actual time=0.003..0.006 rows=5 loops=1)
-> Hash (cost=4.83..4.83 rows=1 width=4) (actual time=0.021..0.021
rows=0 loops=1)
-> Index Scan using connection_regid_obj1_index on connection
(cost=0.00..4.83 rows=1 width=4) (actual time=0.013..0.015 rows=1
loops=1)
Index Cond: ((connection_registry_id = 40105) AND (obj1 =
73582))
Total runtime: 0.198 ms

7.4.2:

QUERY
PLAN
----------------------------------------------------------------------------------------------------------------------------------------------------
Hash Join (cost=4.83..5.91 rows=1 width=14) (actual time=0.577..0.600
rows=1 loops=1)
Hash Cond: ("outer".id = "inner".obj2)
-> Seq Scan on rtmessagestate (cost=0.00..1.05 rows=5 width=14)
(actual time=0.006..0.023 rows=5 loops=1)
-> Hash (cost=4.83..4.83 rows=1 width=4) (actual time=0.032..0.032
rows=0 loops=1)
-> Index Scan using connection_regid_obj1_index on connection
(cost=0.00..4.83 rows=1 width=4) (actual time=0.016..0.020 rows=1
loops=1)
Index Cond: ((connection_registry_id = 40105) AND (obj1 =
73582))
Total runtime: 0.697 ms

--Ian