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App very unresponsive while performing simple update

From: Brendan Duddridge <brendan(at)clickspace(dot)com>
To: PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org>
Subject: App very unresponsive while performing simple update
Date: 2006-05-28 09:37:57
Message-ID: 961F6F02-4B00-494C-B071-6DF76A305C14@clickspace.com (view raw or flat)
Thread:
Lists: pgsql-performance
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

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Next:From: Brendan DuddridgeDate: 2006-05-28 09:43:23
Subject: Re: App very unresponsive while performing simple update
Previous:From: Mark KirkwoodDate: 2006-05-28 01:11:47
Subject: Re: is it possible to make this faster?

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