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Oracle8i and histograms ...

By rrq66 ·
Hello to all,
It would need aid on a behavior the optimizer that I do not finish understanding...
Recently the DBA (Oracle8i) has created histograms in columns of tables. Since then the execution plans are quite incomprehensible. Multitude of access 'FULL SCAN' on great tables.
What less I understand is: I see statistics of execution with the plan defined by 'CBO + Histograms' and are worse than those than it could obtain applying 'HIT, s'.
Most peculiar of everything it is that the turnaround time of results of a consultation so and as it is defined is mean to the optimized one with 'HIT, s'!
And if view the number of blocks reads in memory and physicists the answer with 'HINT, s' is 1/10 means part -But takes more!!!-. Somebody could explain to me to that it must east behavior?
Thanks.

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