App very unresponsive while performing simple update

Hi,

Is Postgres supposed to be able to handle concurrent requests while
doing large updates?

This morning I was executing the following simple update statement
that would affect 220,000 rows in my product table:

update product set is_hungry = 'true' where date_modified >
current_date - 10;

But the application that accesses the product table for reading
became very unresponsive while the update was happening.

Is it just a matter of slow I/O? The CPU usage seemed very low (less
than 5%) and iostat showed less than 1 MB / sec throughput.

I was doing the update in psql.

Are there any settings that I could tweak that would help with this
sort of thing?

Thanks,

____________________________________________________________________
Brendan Duddridge | CTO | 403-277-5591 x24 | brendan(at)clickspace(dot)com

ClickSpace Interactive Inc.
Suite L100, 239 - 10th Ave. SE
Calgary, AB T2G 0V9

http://www.clickspace.com