Re: Postgres memory usage

Thanks Jeff:

This is the output of free:

           total      used     free shared buffers cached
Mem:     1031012  1018608    12404      0   64984 848160
-/+ buffers/cache: 105464   925548
Swap:    2040244        0  2040244

shared_buffers and sort_mem are both commented in postgresql.conf:

-bash-2.05b$ grep shared_buf data/postgresql.conf
#shared_buffers = 64        # 2*max_connections, min 16
-bash-2.05b$ grep sort_m data/postgresql.conf
#sort_mem = 512             # min 32

I have verified that postgres is not the responsible for the low
performance of the system, but I just wanted to be sure that memory
usage is reasonable in a postgres installation.

Ruben.



Jeff wrote:

>
> On Sep 16, 2004, at 8:58 AM, ruben20@superguai.com wrote:
>
>> I have noticed that available memory is aparently too low, according
>> to top:
>>
>>  12:58pm  up  1:28,  3 users,  load average: 0,00, 0,01, 0,09
>> 94 processes: 91 sleeping, 3 running, 0 zombie, 0 stopped
>> CPU states:  0,0% user,  0,0% system,  0,0% nice, 100,0% idle
>> Mem:  1031012K av, 1021440K used,    9572K free,       0K shrd,   62864K
>> buff
>> Swap: 2040244K av,   14960K used, 2025284K free                  876808K
>> cached
>>
>
> in the unix world, "free" memory is mostly useless because the OS will
> give up various buffers it is using for caching if an app needs memory.
>  It is usually best to look at the output of free which will show you
> how much of the memory is used by buffers & caches.
>
> If that number is also low you should look to see how much memory your
> applications are using.
>
> Also, what are your shared_buffer and sort_mem settings set to in
> postgresql.conf?
> Remember in Linux top will include how much shared memory an app has
> touched in its SIZE. (But you can also look at the shared column to see
> how much of hte size is shared)
> .
>
>
> --
> Jeff Trout <jeff@jefftrout.com>
> http://www.jefftrout.com/
> http://www.stuarthamm.net/
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
>      joining column's datatypes do not match
>