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TSchmolzi 30 posts Joined 07/07
05 May 2010
Table Design & Performance

When creating tables in Teradata is there an advantage to placing the column(s) that will be used for the Primary Index at the top of the column list?

Also, when several columns in a table are defined as varchar, is there a performance gain when these columns are grouped together at the end of the column list? In other systems this minimizes the amount of data that must be shifted when a value in one of the varchar columns is updated.

- Tim S

tchdk0 6 posts Joined 07/04
05 May 2010

The physical layout of the Teradata record (on the disk) is different than your specification. There is nothing you can do, significant to your basic table specification, that can alter the internal layout. The Database Design manual (under Row Structure) explains this.

TSchmolzi 30 posts Joined 07/07
05 May 2010

By placing columns in the order described by the TD12 Database Design Manual p801+ (fixed,compressed, variable) would it save the system time/resources by avoiding an internal reorder of the columns?

- Tim S

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