RE: index range scan vs. an index full scan

From: Powell, Mark D <mark.powell_at_EDS.COM>
Date: Tue, 4 May 2004 13:43:08 -0400
Message-ID: <564DE4477544D411AD2C00508BDF0B6A1CE0AB0A@usahm018.exmi01.exch.eds.com>

Statistics and the where clause conditions influence the CBO decision on the choice between a range scan and a full index scan. The skew of the data, bind vs constant is submitted SQL, and existence of histograms all potentially come into play. A specific SQL statement example with an explain plan for each choice (range vs full) against the same tables, along with table column statistics for indexed columns, and the list of indexes might allow someone to provide a more specific answer.

HTH -- Mark D Powell --

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of ryan.gaffuri_at_cox.net Sent: Tuesday, May 04, 2004 11:59 AM
To: oracle-l_at_freelists.org
Subject: index range scan vs. an index full scan

Sometimes when oracle performs a join it does an index range scan which tend be perform well.

However, sometimes oracle performs an index full scan which does not perform well.

what influences oracles decision in choose what type of index scan to use?

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Received on Tue May 04 2004 - 12:42:00 CDT