

Why wouldn’t Oracle use a perfectly valid index? - lkrubner
http://joco.name/2014/01/05/why-wouldnt-oracle-use-a-perfectly-valid-index/

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lkrubner
I am so stupid that up till now I made the assumption that indexes worked a
lot like histograms. Only when I read this article did I start to think
clearly about how different they are.

