Re: [HACKERS] Postgres Performance

I believe that disk pages are 1k in linux systems, that would mean that
I am allocating 3M when using "postmaster -i -B 3096 -o -S 2048" and 2M
for sorting.  That is very low.  
However, some of the postgres processes have memory segments larger
than 3M (see bottom).

> I would imagine (Im not an expert, but through observation) that if
> you drasticly increase the number of shared memory buffers, then when
> you startup your front-end simply do a select * from the tables, it
> may even keep them all in memory from the start.

That's basically what I tried to do, but I am unable to specify a very
large number (it complained when I tried -B > ~3900).  Do these buffer
contain the actual table data?
I understand that the OS is buffering the data read from disk, but
postgres is competing with all the other processes on the system.  I
think that if postgres had a dedicated (user configurable) cache, like
Oracle, then users could configure the system/postgres better.


4:29pm  up 83 days, 23:42,  5 users,  load average: 0.00, 0.01, 0.00
75 processes: 74 sleeping, 1 running, 0 zombie, 0 stopped
CPU states:  0.1% user,  1.1% system,  0.0% nice, 98.7% idle
Mem:  128216K av,  98812K used,  29404K free,  67064K shrd,  18536K buff
Swap:  80288K av,  22208K used,  58080K free                 14924K
cached
 PID USER     PRI  NI  SIZE  RSS SHARE STAT  LIB %CPU %MEM   TIME
COMMAND
16633 postgres   0   0 26536 1384  1284 S       0  0.0  1.0   0:02
postmaster
18190 postgres   0   0 27708 3432  2720 S       0  0.0  2.6   0:00
postmaster
18303 postgres   0   0 27444 2728  2196 S       0  0.0  2.1   0:00
postmaster
18991 postgres   0   0 27472 2908  2392 S       0  0.0  2.2   0:00
postmaster
19154 postgres   0   0 27408 2644  2140 S       0  0.0  2.0   0:06
postmaster
19155 postgres   0   0 27428 2712  2188 S       0  0.0  2.1   0:00
postmaster
19157 postgres   0   0 27840  10M 10144 S       0  0.0  8.6   0:08
postmaster
19282 postgres   0   0 27560 3332  2732 S       0  0.0  2.5   0:11
postmaster
19335 postgres   0   0 27524 3112  2528 S       0  0.0  2.4   0:03
postmaster
19434 postgres   0   0 27416 2700  2192 S       0  0.0  2.1   0:00
postmaster