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Tera-Tom on Teradata Physical Implementation V12-V13 by Tera-Tom Coffing

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Chapter 7 – Joins

“As I would not be a slave, so I would not be a master. This expresses my idea of democracy.”

- Abraham Lincoln

For two rows to be joined together they must be physically on the same AMP! Wow! That is probably a surprise, but Teradata is an MPP Parallel Processing System. This means that each AMP has its own disk, its own memory, and its own processor. So, like any system the rows will be moved to the AMPs memory and joined in memory. Therefore two rows being joined must be physically together on the same AMP.

The picture on the following page shows you some fundamentals of this concept that are very important for you to get inside your brain.

First of all rows reside on a particular AMP because of the Primary Index Value. ...

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