RE: index range scan vs. an index full scan

From: Khedr, Waleed <Waleed.Khedr_at_FMR.COM>
Date: Tue, 4 May 2004 12:24:27 -0400
Message-ID: <42BBD772AC30EA428B057864E203C99911402E@MSGBOSCLF2WIN.DMN1.FMR.COM>

Range/unique scan always show up when joining to the leading columns of = that index using NL.
Full scan could show up in merge/hash join to replace FTS if it's = cheaper and the joined to columns are not the leading ones. There are other scenarios for Full scan, like reducing the cost of sort, = bad execution plan, etc.

Waleed

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

From: ryan.gaffuri_at_cox.net [mailto: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.=20

what influences oracles decision in choose what type of index scan to = use?=20

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Received on Tue May 04 2004 - 11:28:24 CDT