Histograms Are Evil like Chocolate is Evil

Are you using Histograms to describe your data to the Oracle optimizer? Yes, of course you are – even (especially) if you didn’t know it. Did you want to use them? Are they helping you get to the optimal optimization plan, or making life harder for the optimizer? I will explain the benefits and threats associated with histograms, how the new 12.2 histogram types make them more acceptable,
where they are still a threat and how I usually handle them for greatest benefit in large systems.

 

Video by Timur Akhmadeev at SiOUG 2017

 

 

 

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