Re: A question about performance

Hi,

The optimizer will probably ignore the index and do a full table scan anyway. If not, it would have to do at least two reads (index and data) and still return every row of the table. In any case, leave out the where clause - it could only hurt you.

hth

yosi

TiffanyDu_at_pcdc.com.tw wrote:

> Hi All:
> There is a question about performance.
> Table name : subscriber , primary key : subscr_id , with
> over 5000000 records .
>
> CASE 1 : select *
> from subscriber ;
> (FULL TABLE SCAN)
>
> CASE 2 : select *
> from subscriber
> where subscr_id > 0 ;
> (USE INDEX)
>
> Could anyone tell me which ones performance is better , or
> they are the same ??
>
> Thank you in advance.
>
>
> Tiffany
> E-mail tiffanydu_at_pcdc.com.tw
>
>
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> Author: =?big5?B?VGlmZmFueSBEdSAoIKf5p0qq4iAp?=
> INET: TiffanyDu_at_pcdc.com.tw
>
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Received on Wed Jun 21 2000 - 09:48:01 CDT