Re: 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.

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.

--  Heikki Linnakangas EnterpriseDB   http://www.enterprisedb.com