RE: frequency + height based histograms.

Jaffar

>I was reading Jonathan's great book, at least for me, 'CBO
>Fundamentals' and I got confused of frequency/height based histograms,
>though he explained in a great way.

What is confusing is the name given by Oracle ;-)

>What I understood is that, if we have more than 254 distinct values in
>a columns, we use height based histograms and when we have less than
>254 distinct values in a column, we use one bucket for 1 distinct
>value. Are my assumption are correct, or am I missing something?

if
  "1 distinct value per bucket"
then
  "frequency"
else
  "height-based"
end if

i.e. you may have a height-based histogram even if there are "only" 50 or 100 distinct values. It depends on how you created it.

HTH
Chris

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