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Message Posted: Mon, 21 Apr 2003 @ 16:56:02 GMT

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Subj:   Re: Select * from mytable
From:   Dieter Nöth

Anomy Anom wrote:

  MyTable has tens of millions of rows.  

  The astute user wants to look at the first 2000 rows so they enter:  

There are no _first_ rows in a relational table (without Order By).

  lock MyTable for access
Select * from MyTable;

  Explain says the query will use an all amps retrieve. Why do the nodes take over 2 minutes to start returning rows when there is no one on the system? Based on experience with other database systems I expect the system to start returning rows.  

Teradata first spools _all_ rows and then starts returning data.

Why don't you use a

Select * from MyTable sample 2000;

This will return 2000 random rows.


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