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Home -> Community -> Mailing Lists -> Oracle-L -> [oracle-l] Re: Index block count
What are you checking to see the "block" count ?
v$sess_io
v$sesstat
trace file ?
You've obviously set up a repeatable test, why not send us the output so that we can see the actual figures, and the execution plan.
By the way, if the blevel is two, then an index-only query would have to hit at least three blocks:
root, branch, and leaf.
The blevel is the number of branch levels, and the height is blevel plus one.
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
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I have a b-tree, unique, local, prefixed, range partitioned index. The
blevel
on all of the partitions is 2. There are no chained/migrated rows in the
table.
I have a query that selects 1 record and only uses the index. I am not sure
why
the query uses 4 blocks. I would think that it would just have to use 1 for
the
branch block and 1 for the leaf block. Can someone explain it to me? (I
have
run the query 8,000 times and the average blocks per execution is 4.1)
Thanks,
Tom
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