pg.ddx.io pgsql-performance@postgresql.org mailing list archive
help / color / mirror / Atom feedstart up cost estimate
4+ messages / 3 participants
[nested] [flat]
* start up cost estimate
@ 2006-11-18 09:33 rakesh kumar <trakeshkumar@gmail.com>
0 siblings, 2 replies; 4+ messages in thread
From: rakesh kumar @ 2006-11-18 09:33 UTC (permalink / raw)
To: pgsql-performance
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 .
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: start up cost estimate
@ 2006-11-18 14:27 Joshua Marsh <icub3d@gmail.com>
parent: rakesh kumar <trakeshkumar@gmail.com>
1 sibling, 1 reply; 4+ messages in thread
From: Joshua Marsh @ 2006-11-18 14:27 UTC (permalink / raw)
To: pgsql-performance
On 11/18/06, rakesh kumar <trakeshkumar@gmail.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?
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: start up cost estimate
@ 2006-11-18 18:11 Tom Lane <tgl@sss.pgh.pa.us>
parent: rakesh kumar <trakeshkumar@gmail.com>
1 sibling, 0 replies; 4+ messages in thread
From: Tom Lane @ 2006-11-18 18:11 UTC (permalink / raw)
To: rakesh kumar <trakeshkumar@gmail.com>; +Cc: pgsql-performance
"rakesh kumar" <trakeshkumar@gmail.com> writes:
> I wanted to know , how the start up cost is computed in postgresql
Look into
http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/costsize.c
regards, tom lane
^ permalink raw reply [nested|flat] 4+ messages in thread
* Fwd: start up cost estimate
@ 2006-11-19 04:05 rakesh kumar <trakeshkumar@gmail.com>
parent: Joshua Marsh <icub3d@gmail.com>
0 siblings, 0 replies; 4+ messages in thread
From: rakesh kumar @ 2006-11-19 04:05 UTC (permalink / raw)
To: pgsql-performance
---------- Forwarded message ----------
From: rakesh kumar <trakeshkumar@gmail.com>
Date: Nov 19, 2006 9:31 AM
Subject: Re: [PERFORM] start up cost estimate
To: Joshua Marsh <icub3d@gmail.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@gmail.com> wrote:
>
> On 11/18/06, rakesh kumar < trakeshkumar@gmail.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?
>
>
>
^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2006-11-19 04:05 UTC | newest]
Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2006-11-18 09:33 start up cost estimate rakesh kumar <trakeshkumar@gmail.com>
2006-11-18 14:27 ` Joshua Marsh <icub3d@gmail.com>
2006-11-19 04:05 ` rakesh kumar <trakeshkumar@gmail.com>
2006-11-18 18:11 ` Tom Lane <tgl@sss.pgh.pa.us>
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox