Data Dictionary Cache - DC_HISTOGRAM_DEFS ??

Could somebody explain, what is the above parameter in v$rowcache? I assumed that this cache entries are used by the cost based optimizer, but now I think I could be wrong.

Namely, we have init parameter OPTIMIZER_MODE set to CHOOSE, but since we do not execute any ANALYZE ... statements on any objects, the actual optimizer mode in effect is RULE. With this in mind, I cant see why we have quite some GETS in the dc_histogram_defs cache entries, which ALL results in GETMISSES (the ratio between GETMISSES and GETS is pure 100% !).

Any explanation/suggestion/comment would be appreciated...

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 ! Jurij Modic                            Republic of Slovenia !


 !  tel: +386 61 178 55 14                Ministry of Finance  !

 !  fax: +386 61  21 45 84                Zupanciceva 3        !

 !  e-mail: jurij.modic_at_mf.sigov.mail.si  Ljubljana 1000       !

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