[PERFORM] Table UPDATE is too slow

[Ron St-Pierre]

We have a web based application with data that is updated daily. The 
biggest bottleneck occurs when we try to update
one of the tables. This table contains 58,000 rows and 62 columns, and 
EVERY column is indexed. Every column is
queryable (?) by the users through the web interface so we are 
reluctant to remove the indexes (recreating them would
be time consuming too). The primary key is an INT and the rest of the 
columns are a mix of NUMERIC, TEXT, and DATEs.
A typical update is:
  UPDATE dataTable SET field01=44.5, field02=44.5, field03='Bob',
    field04='foo', ... , field60='2004-08-30', field61='2004-08-29'
    WHERE id = 1234;

Also of note is that the update is run about 10 times per day; we get 
blocks of data from 10 different sources, so we pre-process the
data and then update the table. We also run VACUUM FULL ANALYZE on a 
nightly basis.

Does anyone have some idea on how we can increase speed, either by 
changing the updates, designing the database
differently, etc, etc? This is currently a big problem for us.

Other notables:
  The UPDATE is run from a within a function: FOR rec IN SELECT ...LOOP 
RETURN NEXT rec; UPDATE dataTable.....
  Postgres 7.4.3
  debian stable
  2 GB RAM
  80 DB IDE drive (we can't change it)

  shared_buffers = 2048
  sort_mem = 1024  
  max_fsm_pages = 40000
  checkpoint_segments = 5
  random_page_cost = 3

Thanks

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Ron

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