aa8d7cd2_Cost_Based_Oracle_Fundamentals__Comments
[Chapter] Chapter 3 [Last addendum] 1st April 2006 [Title] Single table selectivity [Comments] 
How many rows will a simple query produce? This is one of the cornerstones of picking a good execution plan. The cardinality (number of rows) is derived from the selectivity (fraction of rows) – and it is surprising how many variations there are in the calculation of selectivity – even for a single table.
Cost Based Oracle Fundamentals
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