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Re: two queries and dual cpu (perplexed)

From: Jeff <threshar(at)torgo(dot)978(dot)org>
To: "Shoaib Burq (VPAC)" <sab(at)vpac(dot)org>
Cc: performance pgsql <pgsql-performance(at)postgresql(dot)org>
Subject: Re: two queries and dual cpu (perplexed)
Date: 2005-04-22 11:48:29
Message-ID: (view raw or whole thread)
Lists: pgsql-performance
On Apr 21, 2005, at 11:33 PM, Shoaib Burq (VPAC) wrote:

> BTW I guess should mention that I am doing the select count(*) on a 
> View.

A bit of a silly question...
but are you actually selecting all the rows from this query in 
production or would it be more selective?  ie select * from bigslowview 
where bah = 'snort'?

> Ran the Explain analyse with the nestedloop disabled but it was taking
> forever... and killed it after 30mins.

If it takes too long you can run just plain explain (no analyze) and it 
will show you the plan.  This is nearly always instant... it'll give 
you a clue as to if your setting changes did anything.

You may need to end up breaking some parts of this up into subqueries.  
I've had to do this before.  I had one query that just ran too dang 
slow as a join so I modified it into a subquery type deal.  Worked 
great.  However since you are selecting ALL rows I doubt that will help 

Another option may be to use materialized views.  Not sure how 
"dynamic" your data model is. It could help.

Jeff Trout <jeff(at)jefftrout(dot)com>

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