I was reading through a few Teradata material and came across this statement:
"Unique Primary Index cannot be defined when the partition column is nor part of Primary Index" .
And my questions is : WHY ??? I checked with a few serior colleques and all of have the same question. Why ?
I believe that there is nothing wrong in defining Unique Primary index when PPI is defined, though it might not add much value. But why did Teradata enforce this restriction ?
This was discussed to death some time ago on another thread in this forum:
The short answer is that it would be too expensive to enforce uniqueness constraint.