URGENT: Performance tuning

Hi ,

I need info about how to fine tune my postgresql.

I make a little test and the results was not good for posgresql.

I will to use the server in production and need this info.

So, the test:

first machine:

Linux Mandrake 8.2 and posgresql on it.

Dual Athlon MP 1,6 GHz , 1 GB RAM , IDE 7200 40 GB HDD.

I create a litle table (field1 varchar(100),field2 varchar(100), field3 int) and fill

200 000 x ('aaaaaaaaaaaaa1','bbbbbbbbbbbbbbb1',10);

200 000 x ('aaaaaaaaaaaaa2','bbbbbbbbbbbbbbb2',20);

200 000 x ('aaaaaaaaaaaaa3','bbbbbbbbbbbbbbb3',30);

200 000 x ('aaaaaaaaaaaaa4','bbbbbbbbbbbbbbb4',40);

200 000 x ('aaaaaaaaaaaaa5','bbbbbbbbbbbbbbb5',50);

After that i make : select distinct field1 from mytable.

As result I get 5 rows and it is OK, but the time is 3 min 30 sec.

The processor usage is 50% - it is OK , and the system use the maximum of the first processor.

The second machine:

Athlon XP 1,5 GHz , 512 MB RAM , 7200 HDD 40 GB

WinNT 4, Oracle 8i.

I make the same test.

The result come for 15 sec !!!!.

Ok, I am sure : the diferent can not be so big.

I do not make any special setup an postgres and on linux, anly the standart install.

Any info or example will be great.

Many thanks in advance.