Re: RE: OR Vs UNION

[rgaffuri]

the algorithm for 'or' is simply a series of key value searches right that is short 
circuited right?

oracle searches to see if the first value exists, if it does, stop, else look for the 
second value.

then turns that into a resultset correct? 
> 
> From: "Ganesh Raja" <[EMAIL PROTECTED]>
> Date: 2003/06/24 Tue PM 12:25:02 EDT
> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
> Subject: RE: OR Vs UNION
> 
> IMHO ... 
>  
> Cannot be.. the Access Path Taken is Different.. "OR" is Transfered to
> Inlist Iterator usually ... 
>  
> Best Regards,
> Ganesh R
> DID : +65-6215-8413
> HP  : +65-9067-8474
> ===========================================
> Live to learn... forget... and learn again.
> ===========================================
> 
> 
> -----Original Message-----
> Jamadagni, Rajendra
> Sent: Tuesday, June 24, 2003 11:10 PM
> To: Multiple recipients of list ORACLE-L
> 
> 
> 
> I believe OR is internally transformed to UNION (or UNION ALL) ?? 
> 
> The answer you are looking is ... test and measure it in _your_
> _environment_. 
> 
> Raj 
> ------------------------------------------------------------------------
> -------- 
> Rajendra dot Jamadagni at nospamespn dot com 
> All Views expressed in this email are strictly personal. 
> QOTD: Any clod can have facts, having an opinion is an art ! 
> 
> >----- ------- Original Message ------- ----- 
> >From: [EMAIL PROTECTED] 
> >To: Multiple recipients of list ORACLE-L 
> ><[EMAIL PROTECTED]> 
> >Sent: Mon, 23 Jun 2003 21:34:52 
> > 
> > 
> > 
> > 
> > 
> >Hi All, 
> > 
> >Could someone explain to me which one is best in 
> >the following two queries 
> >w.r.t performance? 
> > 
> >Thanks 
> >Sami 
> > 
> >Query1) 
> >======== 
> >select distinct empployee_id from employees where 
> >department_id=10 or 
> >department_id=20 
> >/ 
> > 
> >Query2) 
> >======= 
> >select employee_id from employees where 
> >department_id=10 
> >union 
> >select employee_id from employees where 
> >department_id=20 
> >/ 
> > 
> 
> 
> 

Title: Message

IMHO ...

 

Cannot be.. the Access Path Taken is Different.. "OR" is Transfered to Inlist Iterator usually ...

 

Best Regards,
Ganesh R
DID : +65-6215-8413
HP  : +65-9067-8474
===========================================
Live to learn... forget... and learn again.
===========================================

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jamadagni, Rajendra
Sent: Tuesday, June 24, 2003 11:10 PM
To: Multiple recipients of list ORACLE-L
Subject: RE: OR Vs UNION

I believe OR is internally transformed to UNION (or UNION ALL) ??

The answer you are looking is ... test and measure it in _your_ _environment_.

Raj
--------------------------------------------------------------------------------
Rajendra dot Jamadagni at nospamespn dot com
All Views expressed in this email are strictly personal.
QOTD: Any clod can have facts, having an opinion is an art !

>----- ------- Original Message ------- -----
>From: [EMAIL PROTECTED]
>To: Multiple recipients of list ORACLE-L
><[EMAIL PROTECTED]>
>Sent: Mon, 23 Jun 2003 21:34:52
>
>
>
>
>
>Hi All,
>
>Could someone explain to me which one is best in
>the following two queries
>w.r.t performance?
>
>Thanks
>Sami
>
>Query1)
>========
>select distinct empployee_id from employees where
>department_id=10 or
>department_id=20
>/
>
>Query2)
>=======
>select employee_id from employees where
>department_id=10
>union
>select employee_id from employees where
>department_id=20
>/
>