>>> On Tue, Mar 4, 2008 at  8:42 AM, in message
<[EMAIL PROTECTED]>, Chris Kratz
<[EMAIL PROTECTED]> wrote: 
 
> So, I've now been asked to ping the list as to whether turning off  
> nested loops system wide is a bad idea, and why or why not.
 
In our environment, the fastest plan for a lot of queries involve
nested loops.  Of course, it's possible that these never provide the
fasted plan in your environment, but it seems very unlikely --
you're just not noticing the queries where it's doing fine.
 
> Any other thoughts or suggestions?
 
Make sure your effective_cache_size is properly configured.
 
Increase random_page_cost and/or decrease seq_page_cost.
You can play with the cost settings on a connection, using EXPLAIN
on the query, to see what plan you get with each configuration
before putting it into the postgresql.conf file.
 
-Kevin
 



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