Re: problem with from_collapse_limit and joined views

Markus Schulz  11/24/10 1:02 PM >>>
 
> if i set "from_collapse_limit" (to merge the views) and
> join_collapse_limit (to explode the explicit joins) high enough
> (approx 32), all is fine (good performance). But other queries are
> really slow in our environment (therefore it's no option to raise
> the join_collapse_limit to a higher value)
> 
> With defaults (8) for both, the performance is ugly
 
One option would be to create a different user for running queries
which read from complex views such as this.  
 
postgres=# create user bob;
CREATE ROLE
postgres=# alter user bob set from_collapse_limit = 40;
ALTER ROLE
postgres=# alter user bob set join_collapse_limit = 40;
ALTER ROLE
 
Log in as bob, and your queries should run fine.
 
Nothing leapt out at me as an issue in your postgresql.conf except:
 
max_prepared_transactions = 20
 
Do you actually use prepared transactions?  (Sometimes people confuse
this with prepared statements, which are a completely different
feature.)
 
-Kevin