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Re: [PERFORM] poor performance in migrated database

From: Carlos Lopez <chlopezl(at)yahoo(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-performance(at)postgresql(dot)org, pgsql-admin(at)postgresql(dot)org
Subject: Re: [PERFORM] poor performance in migrated database
Date: 2004-11-09 14:56:31
Message-ID: 20041109145631.86002.qmail@web52710.mail.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-adminpgsql-performance
Dear Tom,
thanks for your information.
Where can I learn more about the explain and analyze??
One view that is giving a lot of problems is vkardex_3
which is used most of the time...
The explain analyze I sent is one of the views that
conform this one.

Thanks in advance.
Carlos Lopez Linares


--- Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Carlos Lopez <chlopezl(at)yahoo(dot)com> writes:
> > This is one of the queries that work,and is the
> first
> > in a 4 level nested query....
> 
> Do you really need UNION (as opposed to UNION ALL)
> in this query?
> The EXPLAIN shows that almost half the runtime is
> going into the
> sort/uniq to eliminate duplicates ... and according
> to the row
> counts, there are no duplicates, so it's wasted
> effort.
> 
> I looked at your schema and saw an awful lot of
> SELECT DISTINCTs
> that looked like they might not be necessary, too. 
> But I'm not
> willing to crawl through 144 views with no
> information about
> which ones are causing you problems.  What's a
> typical query
> that you are unsatisfied with the performance of?
> 
> 			regards, tom lane
> 


=====
___
Ing. Carlos Lpez Linares
IT Consultant
Quieres aprender linux?
visita http://www.aprende-linux.com.sv

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