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Message Posted: Fri, 06 Sep 2002 @ 14:30:54 GMT

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Subj:   Re: Why all-amp macro?
From:   Frank O Connor


In the macro, you have asked the macro to do a full table scan. Teradata has to do a full scan of the table to get the data and it may not be always be sure that there is data on one amp (eg stale or no stats - teradata does not know if the stats are stale or not).

You will only get a single amp operation if you provide a distinct and single limit to a primary index value.

So if your macro has a predicate such as :

select *
FROM facdiscready

Then a single amp operation will occur.

Finally, you may need to consider your primary index choice. I assume from your question that your primary index contains a constant value. This means that the table relies on one amp and you are likely to suffer performance problems as you are not using the parallelism of Teradata.

God Luck


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