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Archives of the TeradataForum
Message Posted: Thu, 22 May 2003 @ 18:37:29 GMT
| Subj: | | Re: Time Stamp in Teradata |
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| From: | | Dieter N�th |
Geoffrey Rommel wrote:
| | So if you select without ORDER BY you'll always end up with an unordered result set. This is different to most other
RDBMSes. | |
| | I hesitate to disagree with Dieter, but this is not quite correct. | |
You're welcome, don't hesitate ;-)
| | In relational theory, relations are sets, so they are unordered. For instance, the set {integers between 1 and 20} can be
enumerated in a conventional order -- 1, 2, 3, etc. -- but there is no order to the set itself; all 20! enumerations specify the same
set. | |
Yep: "So if you select without ORDER BY you'll always end up with an unordered result set."
| | In other RDBMSes, the rows may in fact come out in the same order every time, | |
even in Teradata
| | but this is merely a by-product of the physical ordering on disk; it does not imply that there is an order to the rows of the
table. | |
Yep: "This is different to most other RDBMSes."
Teradata is just closer to the relational model than other databases ;-)
So, i really don't see where we disagree.
Dieter
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