"Aleksandr Vinokurov" <[EMAIL PROTECTED]> writes:
> And that is its plan (attached one is the same, but with costs):
>
>>---------------------------------<cut>--------------------------------<
> Merge Left Join
> Merge Cond: ("outer".name = "inner".name)
> -> Sort
> Sort Key: log.name
> -> Seq Scan on log_example_3 log
> -> Sort
> Sort Key: uh.name
> -> Subquery Scan uh
> -> Sort
> Sort Key: name
> -> Seq Scan on user_history
>>---------------------------------<cut>--------------------------------<
What version are you running with?
Incidentally with CVS HEAD I see it working:
postgres=# explain select * from (select * from a order by i) as a right join b
on a.i = b.i ;
QUERY PLAN
-----------------------------------------------------------------
Merge Right Join (cost=299.56..675.13 rows=22898 width=16)
Merge Cond: (public.a.i = b.i)
-> Sort (cost=149.78..155.13 rows=2140 width=8)
Sort Key: public.a.i
-> Seq Scan on a (cost=0.00..31.40 rows=2140 width=8)
-> Sort (cost=149.78..155.13 rows=2140 width=8)
Sort Key: b.i
-> Seq Scan on b (cost=0.00..31.40 rows=2140 width=8)
(8 rows)
> With best regards to all of you,
> Aleksandr.
> ÿþ M e r g e L e f t J o i n
> ( c o s t = 2 0 7 6 4 6 . 0 0 . . 2 1 3 8 6 4 . 1 2 r o w s = 3 4 7 8 5 1
> w i d t h = 6 2 ) ( a c t u a l
> t i m e = 3 0 9 2 2 . 3 6 6 . . 3 2 1 6 6 . 5 1 8 r o w s = 1 3 9 0 8
> l o o p s = 1 )
> M e r g e C o n d : ( " o u t e r " . n a m e =
> " i n n e r " . n a m e )
> - > S o r t ( c o s t = 6 . 7 1 . . 7 . 0 3 r o w s = 1 2 7
> w i d t h = 3 0 ) ( a c t u a l t i m e = 1 . 1 1 7 . . 1 . 2 0 7
> r o w s = 1 0 0 l o o p s = 1 )
> S o r t K e y : l o g . n a m e
> - > S e q S c a n o n l o g _ e x a m p l e _ 3
> l o g ( c o s t = 0 . 0 0 . . 2 . 2 7 r o w s = 1 2 7
> w i d t h = 3 0 ) ( a c t u a l t i m e = 0 . 0 5 3 . . 0 . 1 7 7
> r o w s = 1 0 0 l o o p s = 1 )
> - > S o r t
> ( c o s t = 2 0 7 6 3 9 . 2 9 . . 2 0 9 0 0 8 . 7 8 r o w s = 5 4 7 7 9 6
> w i d t h = 3 2 ) ( a c t u a l
> t i m e = 3 0 9 2 1 . 1 7 1 . . 3 1 4 6 7 . 1 1 7 r o w s = 4 4 2 8 4 8
> l o o p s = 1 )
> S o r t K e y : u h . n a m e
> - > S u b q u e r y S c a n u h
> ( c o s t = 1 1 1 4 4 7 . 9 0 . . 1 1 8 2 9 5 . 3 5 r o w s = 5 4 7 7 9 6
> w i d t h = 3 2 ) ( a c t u a l
> t i m e = 1 9 2 7 7 . 9 6 3 . . 2 1 5 9 5 . 8 7 4 r o w s = 5 4 7 7 9 6
> l o o p s = 1 )
> - > S o r t
> ( c o s t = 1 1 1 4 4 7 . 9 0 . . 1 1 2 8 1 7 . 3 9 r o w s = 5 4 7 7 9 6
> w i d t h = 3 2 ) ( a c t u a l
> t i m e = 1 9 2 7 7 . 9 0 8 . . 2 0 1 0 4 . 5 6 8 r o w s = 5 4 7 7 9 6
> l o o p s = 1 )
> S o r t K e y : n a m e
> - > S e q S c a n o n
> u s e r _ h i s t o r y ( c o s t = 0 . 0 0 . . 2 2 1 0 3 . 9 6
> r o w s = 5 4 7 7 9 6 w i d t h = 3 2 ) ( a c t u a l
> t i m e = 0 . 0 5 1 . . 1 4 7 4 . 1 4 3 r o w s = 5 4 7 7 9 6
> l o o p s = 1 )
gesundheit.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
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TIP 6: explain analyze is your friend
