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Message Posted: Tue, 05 Feb 2008 @ 12:55:10 GMT


     
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Subj:   Dealing with concentrated values in the data
 
From:   Anomy Anom

<-- Anonymously Posted: Tue, 5 Feb 2008 07:41 -->

We have some tables that have concentrated values within the NUPI.

CASE 1: 10M row table; 1M rows with modal value Normal_Tuesday

CASE 2: 10M row table; 100K rows with modal value FAT_Tuesday

CASE 3: 10M row table; 10K rows with modal value Super_Tuesday

CASE 4; 10M row table; 1k have the with modal value Tuesday


Row lengths are 125 bytes, blocking is at 128K, so ~1000 rows per block.

What is the performance impact on loads in the cases?

What is the performance impact on queries that target the modal value?

What is the performance hit on table scans with residual conditions involving joins on the PI to another table with

a) same PI

b) different PI


Thank-you for your help.



     
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