Query taking a long time...

Hi all,

I've just added a new column to a table, and I am updating it to have a
value. The table has only 18000 rows, and yet the query takes in the order
of 10 minutes to complete. This is the process running:

last pid: 57224; load averages: 0.40, 0.50, 0.59 up 1+18:57:41
19:00:34
75 processes: 1 running, 74 sleeping
CPU states: 6.6% user, 0.0% nice, 6.2% system, 0.8% interrupt, 86.4%
idle
Mem: 234M Active, 76M Inact, 45M Wired, 18M Cache, 48M Buf, 952K Free
Swap: 521M Total, 324K Used, 521M Free

PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND
56770 pgsql -6 0 24884K 20956K biord 2:14 10.11% 10.11% postgres

My postgresql.conf settings:

max_connections = 128
sort_mem = 2048
shared_buffers = 2048
log_timestamp = true

The machine has a Seagate SCSI 40mb/sec HDD, running at some fast mhz that I
can't quite remember (1Ghz?)

Surely it should take a lot less than 10 minutes to touch 18000 rows!!!

Chris