Postgres Table grows very quickly?

I have a postgres database that I use to keep stats on my routers. I have a
separate table for each router and another called routerinfo where I keep
model information and the time and date each of the seperate router tables
have been updated.

Routerinfo has 16 rows (for 16 routers) it gets updated every five minutes
with the last date and time each of the other tables have been updated. I
use a standard sql update statement. eg:

UPDATE routerinfo SET lastdate = '09-14-1999', lasttime = '09:00' WHERE
linkid = 'Sydney';

Routerinfo is 8k after the initial update, from then on it grows 8k for
every update. I never do an insert and it never grows beyond 16 rows. It
seems as if the table is keeping a history of all updates, but timetravel is
disabled in the current release of postgres, so that can't be it. If anybody
has any idea of how I can stop this, please let me know

Thank you.

Michael Green
Senior Systems Engineer
Communications Systems
Global Banking & Securities Transactions
http://www.gbst.com.au
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