From: Gregory Stark <stark@enterprisedb.com>
To: Aleksandr Vinokurov <aleksandr.vin@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Incomprehensible dogged sort in Merge Join
Date: Fri, 31 Aug 2007 15:45:37 +0100
Message-ID: <877inb225q.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <46D82318.3070700@gmail.com>
References: <46D82318.3070700@gmail.com>
"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 ;
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.
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To: pgsql-sql@postgresql.org
Cc: stark@enterprisedb.com, aleksandr.vin@gmail.com
Subject: Re: Incomprehensible dogged sort in Merge Join
In-Reply-To: <877inb225q.fsf@oxford.xeocode.com>
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