Rule Based Optimizer

GreyBeard · *nix forums Guru Wannabe Joined: 10 Mar 2005 Posts: 182

Assuming we are talking about "Index Unique Scan' and 'Index Range Scan',
these are described in the Concepts manual - for 9iR2 in Chapter 10, under
Indexes, in the section "How Indexes Are Searched"

In the docco, the difference is basically:

Unique scan: find a matching key and return the rowid
Range scan: for each key between lower and upper bound, return rowid

For the exact details, see

http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c11schem.htm#3239

hth/FGB

amerar@iwc.net · *nix forums Guru Wannabe Joined: 27 Jul 2005 Posts: 185

Hi All,

The application I am in charge of has been optimized to use the rule
based optimizer. I've been doing some tracing and would like some
clarification.

What is the difference between a UNIQUE SCAN and a RANGE SCAN?

I'm lost as the to differences. Even the documentation does not really
tell me the difference between them.

Thanks,

Arthur

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