# Thread: Find Out The Logical Read Per Row Using An Index

1. Junior Member
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## Find Out The Logical Read Per Row Using An Index

Oracle version is 9.2.0.3.0
O/s is Sun 64 bit ver 9

My aim is to find out the logical read per row using a particular index. In schema everything is analyzed. So is there any view or process to find out it ?

Say for example, If an index has blevel is 2, avg_data_blocks_per_key is 335 and avg_leaf_blocks_per_key 662 and distinct key is 20, then can I say that LRPR (logical read per row) is 34 which is cost.I am calculating this figure in the following way

Cost is (2*662)/20 i.e 67 for traversing each key for that index.
Cost is 337 since 337 blocks need to be scanned for each key value.

The no. of records for that key is say 10.

cost for 1 row of that key for index traversing is 67/10 = 7

cost for one row of that key from table (337/10) = 38

Approximately the ultimate cost is 38 + 7 = 45 for each row of that key value using this index.

I assume that I am not collecting any system stats.So it will not affect the behaviour of optimizer.

Regards

Deba

2. Pando & Company
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select * from v\$segment_statistics

3. Junior Member
Join Date
Oct 2001
Location
Calcutta , India
Posts
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Hi Pando,

What u r trying to say is not clear. Will u explain it ?

Thanks

Deba

4. Pando & Company
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I dont understand why you are calculating something meaningless such as cost!

5. Originally posted by pando
I dont understand why you are calculating something meaningless such as cost!
Hell, I don't understand why you would want to find out the logical read per row using a particular index in the first place. Sounds like working harder not .....

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