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