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How is optimization calculated on a query

From: <ricke1_at_my-dejanews.com>
Date: Fri, 25 Sep 1998 22:23:07 GMT
Message-ID: <6uh54a$u22$1@nnrp1.dejanews.com>


I have been trying to do a select on a table like select
c1, c2
from t1
where
c1='01-jan-1997'
order by c2;
I have 2 indexes, one on c1 and one on c2. Yet the execution plan sometimes shows a full table scan.
I have played with the parameters, optimizer_mode and optimizer_percent_parallel.
I've done various versions of analyze table and analyze index. I didn't want to do explicit hints, but have tried /*+index*/ and surprisingly (to me) still got a full table scan sometimes. I am running 8.0.4 on an NT4 enterprise system, multiple cpus. I'd like to get a consistent plan for timings, preferably the faster index search. Any ideas would be appreciated. Thanks -Rick

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