Bad update performance?

Hi there,

I´ve a table with about 142000 rows like shown below and I want to set field
"divis" to "unknown" by executing following update command:
update ipacct set divis = 'unknown';

However this seems to take hours, I´ve a PII 350MHz with 192Mb memory and
Quantum UIDE disk, is there a way for me to speed up the update process
except for switching to a SCSI hard drive? Does indexing the field "divis"
speed up the update performance?

The load on the machine is about 1,5 to 2 all the time and it´s hacking on
the hard drive like hell.
I´ve the same problem when I do "UPDATE ipacct SET traf = (src+dst)", it
takes hours. Is this normal? Is there another way to do this?

However reading from the database doing select is very fast.

Many thanks in advance for any hint,
best regards,
Gunnar Ingvi Thorisson

CCIE 4826
Iceland
gunni(at)if(dot)is

venus:~$ psql ipacct
Welcome to the POSTGRESQL interactive sql monitor:
Please read the file COPYRIGHT for copyright terms of POSTGRESQL
[PostgreSQL 6.5.0 on i686-pc-linux-gnulibc1, compiled by gcc 2.7.2.3]

[cut]

ipacct=> select * from ipacct where id = 1;
id| datetime|pcol|saddr |sport|daddr |dport|pcnt| size|if
|login |mac |src|dst|traf|depart|divis
--+---------+----+-----------------+-----+------------+-----+----+-----+----
+-------+------------+---+---+----+------+-----
1|928368167| 6|209.85.127.151/32| 80|10.10.2.3/32| 2448|
57|74856|eth0|unknown|00805FC1525C|100| 3| 103| |
(1 row)

ipacct=> update ipacct set divis = 'unknown';

The table:
ID INT4 UNIQUE,
DATETIME TEXT,
PCOL INTEGER,
SADDR CIDR,
SPORT INTEGER,
DADDR CIDR,
DPORT INTEGER,
PCNT INT4
SIZE INT4;
IF TEXT;
LOGIN TEXT;
MAC TEXT;
SRC INTEGER;
DST INTEGER;
TRAF INTEGER;
DEPART TEXT;
DIVIS TEXT;