Re: Incomprehensible dogged sort in Merge Join

"Aleksandr Vinokurov" <aleksandr.vin@gmail.com> 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 ;
QUERYPLAN                             
-----------------------------------------------------------------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)
SortKey: 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