Tuesday, February 15, 2011

How Teradata makes sure that there are no duplicate rows being inserted when it’s a SET table?


How Teradata makes sure that there are no duplicate rows being inserted when it’s a SET table?
Answers:

Teradata will redirect the new inserted row as per its PI to the target AMP (on the basis of its row hash value), and if it find same row hash value in that AMP (hash synonyms) then it start comparing the whole row, and find out if duplicate.
If it’s a duplicate it silently skips it without throwing any error.

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