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Re: how to interpret dbms_xplan.display

From: srivenu <srivenu_at_hotmail.com>
Date: 11 May 2004 00:36:21 -0700
Message-ID: <1a68177.0405102336.41f5ea50@posting.google.com> 





The cardinality of INDEX UNIQUE SCAN shows the full cardinality of the
table.


And the cardinality of TABLE ACCESS BY INDEX ROWID that follows it
shows as 1.



Whereas if you have an INDEX RANGE SCAN, the cardinality shows the
number of rows that would be returned. And the TABLE ACCESS BY INDEX
ROWID that follows it shows the same cardinality (provided there are
no additional predicates on the other table columns).



The cost is normally the number of I/O calls issued.
regards


Srivenu
Received on Tue May 11 2004 - 02:36:21 CDT












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