From: | "Ross J(dot) Reedstrom" <reedstrm(at)rice(dot)edu> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: What is a "tuple" |
Date: | 2001-06-22 17:28:02 |
Message-ID: | 20010622122802.C14381@rice.edu |
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Lists: | pgsql-sql |
On Fri, Jun 22, 2001 at 06:31:03PM +0200, Kristoff Bonne wrote:
> Greetings, (and also Alex)
>
> On Fri, 22 Jun 2001, Josh Berkus wrote:
> > > Excuse my lack my 'database'-jargon, but what is a 'tuple'?
>
> > Also known as a "Record", or a "Row". The word "tuple" is used because
> > it can refer to a row returned as part of a result set as well as a
> > record in a table. Strictly speaking, a row returned from most queries
> > is not a record, as that row does not exist in permanent storage
> > anywhere .... it is created by the query. Hence, "tuple".
It's probably a back formation from the suffix 'tuple' as in the sequence:
single, double, triple, quadruple, quintuple, sextuple, septuple, ...
So, mathematicians generalized this (as is their wont) to
[algebraic expression]-tuple, such as:
n-tuple, (n^2)-tuple
Which found their way to The Relational Algebra, simplified to just
'tuple' and hence, to SQL.
Ross (way to much detail!) Reedstrom
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