RE: A question about performance

Re-read the reply.

It does make a difference.

George.

> -----Original Message-----
> From: "Singla, Sanjeev" <SSingla_at_oxhp.com> [mailto:SSingla_at_oxhp.com]
> Sent: Wednesday, June 21, 2000 5:50 PM
> To: SMTP_at_INL002@Servers["Multiple recipients of list ORACLE-L"
> <ORACLE-L_at_fatcity.com>]
> Subject: RE: A question about performance
>
>
> Distribution of data does not make any difference because he
> is scanning the
> entire table,
> so it has to scan all the blocks anyway.
> So in this table full scan will be better.
>
>
> -----Original Message-----
> [mailto:George.Brennan_at_warnermusic.com]
> Sent: Wednesday, June 21, 2000 11:48 AM
> To: Multiple recipients of list ORACLE-L
>
>
> Why is everyone jumping to conclusions about the data?
>
> What is the distribution of the values in the table?
> How many rows per data block?
> etc.
>
> If there are > 10% ( or so ) with a value >= 0 then the index
> may be faster.
> If there are > 10% ( or so ) with a value <= 0 then the index
> may be slower.
>
> e.g. a PK col + long col may only be 1 row per block that may
> screw you
> ideas up a bit. :-)
>
> George
>
> > -----Original Message-----
> > From: "Singla, Sanjeev" <SSingla_at_oxhp.com> [mailto:SSingla_at_oxhp.com]
> > Sent: Wednesday, June 21, 2000 3:30 PM
> > To: SMTP_at_INL002@Servers["Multiple recipients of list ORACLE-L"
> > <ORACLE-L_at_fatcity.com>]
> > Subject: RE: A question about performance
> >
> >
> > Full table scan will be faster.
> > Reason: If it go for index scan it will get the rowids
> > and come back
> > with those
> > rowids to scan the table because u are selecting all the
> > columns so it has
> > to do full
> > scan of table also for getting everything.
> > Index scan + full scan of table for actual data. (If going
> > for index scan)
> > ----------- Only table scan for actual blocks (Full scan)
> >
> > Cheers.
> >
> > -----Original Message-----
> > Sent: Tuesday, June 20, 2000 11:35 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > 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
> >
> >
> > --
> > Author: =?big5?B?VGlmZmFueSBEdSAoIKf5p0qq4iAp?=
> > INET: TiffanyDu_at_pcdc.com.tw
> >
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> > --
> > Author: Singla, Sanjeev
> > INET: SSingla_at_oxhp.com
> >
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>
> --
> Author:
> INET: George.Brennan_at_warnermusic.com
>
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> --
> Author: Singla, Sanjeev
> INET: SSingla_at_oxhp.com
>
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Received on Wed Jun 21 2000 - 11:41:29 CDT