bitmap index and distinct values

  • From: Cee Pee <carlospena999@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Tue, 21 Apr 2015 22:37:03 -0500

Hi all,

I was doing some reading on the internet about bitmap index suitability as
it relates to the number of distinct values. I came across several links 1
<http://www.dba-oracle.com/t_bitmap_index_maximum_distinct_values_cardinality.htm>,
2
<https://richardfoote.wordpress.com/2010/02/18/myth-bitmap-indexes-with-high-distinct-columns-blow-out/>,
3 related to the topic. It seems what needs to be considered is the ratio
of distinct values of a column to the total number of rows in the table
rather than considering an absolute number (like over 1,000 or 10,000). Can
someone explain or point to a more descriptive link.

CP.

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