Re: Now I am back, next thing. Final PGS tuning. - Mailing list pgsql-general

From Jennifer Trey
Subject Re: Now I am back, next thing. Final PGS tuning.
Date
Msg-id 863606ec0904080750n4d79128ewe749eda8ed013ff1@mail.gmail.com
Whole thread Raw
In response to Re: Now I am back, next thing. Final PGS tuning.  ("Massa, Harald Armin" <chef@ghum.de>)
List pgsql-general


On Wed, Apr 8, 2009 at 5:38 PM, Massa, Harald Armin <chef@ghum.de> wrote:
Bill, Jennifer,


> *shared_buffers = 1024 # min 128kB or max_connections*16kB  ## Also to low.
> Right? I've got 3GB to work with!*

Assuming that's equating to 1G, then the value is about right.  Common
best practice is to set this value to 1/4 - 1/3 of the memory available
for PostgreSQL.  You're saying you'll have ~3G for PG, so 1G is about
right to start with.


"documenting" that for the wiki is still on my backlog; so, here:

shared_buffers of PostgreSQL on Windows != shared_buffers of PostgreSQL on Unix

My experience is that raising shared_memory on Windows above minimum+~20% is not helping performance; it's more effective to have that memory at Windows for caching. (at least up to server 2003)
I forgot to comment on this on Bill so its good you brought it up again. 
says under shared_buffers 
"If you have a system with 1GB or more of RAM, a reasonable starting value for shared_buffers is 1/4 of the memory in your system."
in your system ... that means I should count from 8GB right? Bill mentioned countring from the 3GB. What would you say Harald, is perhaps 1.5 GB more suitable, a comprise for my giga byte greed :P haha!
 


Harald

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When it comes to the effective_cache I think this might be of great importance for me since similar tuples will be fetched quite often by different users. So caching could become quite important here. 439 MB is not so much. The same guide as mentioned seconds ago says this : 
Setting effective_cache_size to 1/2 of total memory would be a normal conservative setting, and 3/4 of memory is a more aggressive but still reasonable amount.
3/4 of total memory!? Its on 439 MB now. Could someone give me a better offer?
Other things to consider ? 
Sincerely / Jennifer

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