I solved the issue.
I reproduced it immediatly after installing PostgreSQL 8.4.1.
I thougth they were using PostgreSQL 8.4.8 but was never able to reproduce it with that version.
So something was changed related to my problem, but i didn't see explicitly what in the change notes.
Nevermind.
You wrote:
I would leave default_statistics_target alone unless you see a lot of estimates which are off by more than an order of magnitude. Even then, it is often better to set a higher value for a few individual columns than for everything.
We had an issue with a customer where we had to increase the statistics parameter for a primary key.
So I'd like to know if there is a way to identify for which column we have to change the statistics.
Ghislain ROUVIGNAC
2012/12/18 Kevin Grittner <kgrittn@xxxxxxxx>
Ghislain ROUVIGNAC wrote:
> Memory : In use 4 Go, Free 15Go, cache 5 Go.
If the active portion of your database is actually small enough
that it fits in the OS cache, I recommend:
seq_page_cost = 0.1
random_page_cost = 0.1
cpu_tuple_cost = 0.05
> I plan to increase various parameters as follow:
> shared_buffers = 512MB
> temp_buffers = 16MB
> work_mem = 32MB
> wal_buffers = 16MB
> checkpoint_segments = 32
> effective_cache_size = 2560MB
> default_statistics_target = 500
> autovacuum_vacuum_scale_factor = 0.05
> autovacuum_analyze_scale_factor = 0.025
You could probably go a little higher on work_mem and
effective_cache_size. I would leave default_statistics_target alone
unless you see a lot of estimates which are off by more than an
order of magnitude. Even then, it is often better to set a higher
value for a few individual columns than for everything. Remember
that this setting has no effect until you reload the configuration
and then VACUUM.
-Kevin
