We do recommend the creation of System Statistics under certain circumstances for quite a long time. Since Oracle 9i the optimizer works with a CPU and IO cost based model. And in order to give the optimizer some knowledge about the IO subsystem’s performance and throughput – once System Statistics are collected – they’ll get stored in AUX_STATS$. For this purpose in the old Oracle 9i days some default values had been defined – and you’ll still find those defaults in Oracle Database 11g Release 2 in AUX_STATS$. But these old values don’t reflect the performance …
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