Re: System Statistics and the CBO

Wolfgang Breitling wrote:

Patty,

are you sure that is the only thing that changed? From all I know, your system statistics are ignored by the CBO because mreadtim < sreadtim. That is at odds with the CBO's ground rules that scattered reads have to be more "expensive" than sequential reads.

Of course, cardinality is only one aspect of an index' statistics

Wolfgang, when I do SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY) it tells me that "CPU costing is ON, despite
the fact that I fiddled with sys.aux_stats$ and changed sreadtime to be mreadtime+1. Is DBMS_XPLAN lying to me? The
version is 10.1.0.4 on Linux.

--
Mladen Gogala
Oracle DBA
Ext. 121


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