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Re: Will Postgres ever lock with read only queries?

From: Chris <dmagick(at)gmail(dot)com>
To: Robert James <srobertjames(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Will Postgres ever lock with read only queries?
Date: 2009-07-28 01:21:01
Message-ID: 4A6E527D.2070304@gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
Robert James wrote:
> Hi.  I'm seeing some weird behavior in Postgres.  I'm running read only 
> queries (SELECT that is - no UPDATE or DELETE or INSERT is happening at 
> all).  I can run one rather complicated query and the results come 
> back... eventually.  Likewise with another.  But, when I run both 
> queries at the same time, Postgres seems to ground to a halt.  Neither 
> one completes.  In fact, pgAdmin locks up - I need to cancel them using 
> psql.
> I'd expect this from MySQL but not Postgres.  Am I doing something 
> wrong? Or missing something?

They're probably not blocking each other but more likely you're 
exhausting your servers resources. If they return "eventually" 
individually, then running both at the same time will take at least 
"eventually x2".

As Mark said, what are the queries? What postgres version? What o/s? 
What are your hardware specs (how much memory, disk speeds/types etc)?

-- 
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Subject: Re: Will Postgres ever lock with read only queries?
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