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Re: query optimization

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: s(dot)borse(at)direction(dot)biz
Cc: "Julius Tuskenis" <julius(at)nsoft(dot)lt>, pgsql-admin(at)postgresql(dot)org
Subject: Re: query optimization
Date: 2008-07-10 15:47:29
Message-ID: dcc563d10807100847y1d6f5f5ei4e1e380ecc4c3c24@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-admin
On Thu, Jul 10, 2008 at 3:45 AM, Suresh Borse <s(dot)borse(at)direction(dot)biz> wrote:
>
> Good Afternoon !!!
>
> The view executes very faster for the first time.
>
> When I execute the view again and again suddenly it gets slow or it gets
> hang.
>
> I have also traced the query plan but it changes for each execution.Can we
> fix the query plan.
>
> I have also tested the view on my test machine but the result was same.
>
> The view contains multi-table joins.

Do you have different where clauses for each time you execute it?
That can certainly affect performance each time, if you're where
clause is gonna grab 99% of the view, you'll get a different plan than
if you have a where clause that selects 0.01% of the table.

So yeah, we need explain analyze of each type of query that's fast
slow, and if there are ANY differences between them we need to know.

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Subject: Re: query optimization
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