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Fwd: start up cost estimate

From: "rakesh kumar" <trakeshkumar(at)gmail(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Fwd: start up cost estimate
Date: 2006-11-19 04:05:08
Message-ID: 9851130611182005l6cd70e1q7c3a9459fec90f9b@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
---------- Forwarded message ----------
From: rakesh kumar <trakeshkumar(at)gmail(dot)com>
Date: Nov 19, 2006 9:31 AM
Subject: Re: [PERFORM] start up cost estimate
To: Joshua Marsh <icub3d(at)gmail(dot)com>

Hi
                                                  for suppose if I had a
query , something like :


                      select   o_orderpriority

                         from       orders

                          where    o_totalprice < 156163   and exists

(  select   *



from     lineitem



where  l_orderkey = o_orderkey



and l_extendedprice < 38570



)

what is the amount of  cost of EXISTS SUBQUERY  involved in estimate of
totalcost .

 where l_orderkey is part of index of lineitem  , and o_orderkey is primary
key of orders table.
                                             Thanks .


On 11/18/06, Joshua Marsh <icub3d(at)gmail(dot)com> wrote:

>
> On 11/18/06, rakesh kumar < trakeshkumar(at)gmail(dot)com> wrote:
> >
> > Hi ,
> >          I wanted to know , how the start up cost is computed in
> > postgresql . can u give me an example to illustrate the estimation of start
> > up cost .
> >                                                               thanku raa
> > .
> >
>
> It would be very helpful to have a lot more information.  Some questions
> that come to mind:
>
> Approximately how many records will you be storing?
> How big do you think your biggest tables will be?
> How frequently will your biggest tables be accessed (x/day, x/second,
> x/week)?
> Will those accesses be read only, or read/write?
> How important is availability vs. cost?
> Who is your favorite Irish folk singer?
>
>
>

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