High CPU utilization with various index combinations

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04-17-2008, 10:51 PM

Durgaprasad Pawar

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High CPU utilization with various index combinations

Hi,
I have a table with 4 columns (a,b,c,d).

1. Earlier I had defined a UNIQUE constraint on all 4 columns (hence creating a composite index on all 4 columns) and the CPU utilization was ~1/2% during data insertion.
2. However, when I dropped this constraint and created a new UNIQUE constraints on (a,c,d) and (b) the CPU utilization hits 40% during data insertion with same date rate.
3. Also, when I have two unique indexes as (a,b,c,d) and (b) the CPU utilization is very low just like that first case.

Can anyone please explain why there is such a big differencein CPU utilization with different index/constraint combinations?

Regards,
Durgaprasad

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High CPU utilization with various index combinations