Re: postgresql shared buffers

On Fri, 8 Sep 2006, Heikki Linnakangas wrote:

> Date: Fri, 08 Sep 2006 15:22:19 +0100
> From: Heikki Linnakangas <heikki@enterprisedb.com>
> To: Praveen Kumar N <praveen_n@students.iiit.net>
> Cc: pgsql-hackers@postgresql.org
> Subject: Re: [HACKERS] postgresql shared buffers
> 
> Praveen Kumar N wrote:
>> 
>> Following is the output of query i have executed.
>
> Looks like Alvaro guessed right. It reads both relations in sequence, sorts 
> them in temporary storage, outside bufmgr, and then does a merge join on the 
> sorted inputs.

could you tell me how can we trace that? I mean which functions shall I 
checkout for that.


>
> If you want to see the behavior you expected, I think you need to define 
> indexes on a2 and b2, if you don't have them already, and coerce the planner 
> to choose a nested loop join. I'd suggest using "SET enable_seqscan=false; 
> SET enable_bitmapscan=false;" and see if that gets you a nested loop join.
>
>

--  N Praveen Kumar Btech-IV CSE IIIT,Hyd AP,India
    Imagination is more important than knowledge...                                --Albert Einstein