 |
 |
Archives of the TeradataForum
Message Posted: Fri, 13 Oct 2006 @ 10:31:18 GMT
| Subj: | | Re: Index columns reversed in SHOW TABLE |
| |
| From: | | Victor Sokovin |
| | Surely PI is not an index, but can you please let me know why you wouldnt call it 'primary' | |
Vijay, this was partially meant as a joke but a more serious explanation might be as follows. When a person trained on another RDBMS first
encounters the Teradata Primary Index (PI) concept he / she learns that PI is not an index but a key. So, the next confusion would be to think
that PI is a primary key (PK). Of course, it isn't as PI does not need to be unique in Teradata. So, here goes the traditional meaning of the word
"primary" in this context.
Beginners in Teradata definitely need to be careful with this concept and they should not be applying their intuition gained on other RDBMS
when they just hear similar terms. Terminology can be very misleading. So, a catch phrase like "Primary Index is neither Index, nor Primary" may
serve well when we think of the PI. It stops us applying the old knowledge and makes us wonder what the PI really is. Perhaps the next step would
be reading the manual or experimenting with different PI definitions etc.
So, hereby I am coining the phrase but please don't use it during job interviews as yet. It first needs to be generally accepted.
Regards,
Victor
| |
