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Message Posted: Tue, 10 Aug 2004 @ 23:59:59 GMT

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You have not provided any info on the size of your table and the size of your rows. If you have collected statistics and are not seeing a difference, I would think that maybe your table is not very large. I say this because in order for Teradata to use a NUSI you must have statistics collected. At the same time, in order to use a NUSI all AMPs must read their NUSI index blocks to see if they have any of the data values being requested. At a minimum this means two physical reads, one for the index and one for the data block. If your entire table resides on an AMP in two blocks, the optimizer would never ever use the index block. Even if your table resided in 4 blocks on each AMP, that is still the same amount of reads (2 index blocks and 2 data blocks). Again, the NUSI would not be used.

Just a thought,

Michael Larkins
Certified Teradata Master
Certified SQL Instructor

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