Re: Why does sqlplus "select" produce different order of data?

From: David Shi <dshi_at_magpage.com>
Date: 1997/12/06
Message-ID: <66abf2$42u$0@204.179.92.104>#1/1

Parallel Query Option does seem to be the reason, the table I was trying to query has a parallel degree of 6, once I disable that, I got same order each time.

Thanks for all your help.

David

On Thu, 04 Dec 1997 09:07:35 -0500, Allen Kirby <akirby_at_att.com> wrote:

>David Shi wrote:
>>
>> (please also forward your message to dshi_at_magpage.com, thanks a lot)
>>
>> Sorry about posting several questions at the same time, sometimes it's
>> so difficult to get help from Oracle technical support.
>>
>> I noticed when I do a select, each time I got different order of data,
>> is this a Unix buffer problem or something else?
>>
>> Oracle version 7.3.3, OS: Solaris 2.5.1 on a SUN 4000.
>>
><snip>
>
>
>Working as designed. Relational databases do not guarantee the order of
>rows returned from a query unless the order by clause is explicitly
>used. Now, I would have expected the rows to be in the same order,
>especially with a small table, but they don't have to be. Are you using
>the parallel query option? This could change the order. I'm sure it's

     ^^^^^^^^^^^^^^^^^^^^^^

>some kind of internal oracle algorithm intended to improve performance.
>I don't think it would be related to any operating system buffering.
>Just remember if you want it to be ordered, use order by explicitly.
>--
>Allen Kirby
>AT&T Information Technology Services
>Alpharetta, GA.
>The views expressed here are mine, not my employers.
Received on Sat Dec 06 1997 - 00:00:00 CST