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Re: Is it really a performance issue ?

From: yong huang <yong321_at_yahoo.com>
Date: Mon, 24 Jul 2000 07:40:59 -0700 (PDT)
Message-Id: <10568.112756@fatcity.com>


Hi,

I believe it uses more memory to select * than if you select {some columns}. If you have a lot of memory, the performance difference is very little; otherwise the performance problem results from memory shortage, or as Jared said in case of network connection, network bandwidth.

Yong Huang
yong321_at_yahoo.com

you wrote:

Well, I'm making a ( hopefully ) educated guess on this.

The rows will be read regardless of the columns you select.

There will be slightly more overhead to stuff more columns into a cursor, but it is likely negligible.

If you are transporting the data outside of the database, such as to a remote location via SQL*Net, then selecting fewer columns will have a positive impact on performance.

Maybe you could test this out and let us know the results?

Jared

On Fri, 21 Jul 2000, Channa, Santhosh, SITS wrote:

>
>
> > Gurus,
> >
> > I'm wondering if it's a performance issue if i select all the columns from
> > a table even if you don't require.
> >
> > Let say I have a table which has about 50 columns in it and i need to get
> > values for only 5-10 columns. So, instead of selecting only these columns
> > I select *.
> >
> > Any idea if that screws up my performance?
> >
> >
> >
> > Santhosh Babu



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