estimate_selectivity.h

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#ifndef SQL_JOIN_OPTIMIZER_ESTIMATE_SELECTIVITY
#define SQL_JOIN_OPTIMIZER_ESTIMATE_SELECTIVITY
 
class CompanionSet;
class THD;
class Item;
 
/**
  For the given condition, to try estimate its filtering selectivity,
  on a 0..1 scale (where 1.0 lets all records through).
 */
double EstimateSelectivity(THD *thd, Item *condition,
                           const CompanionSet &companion_set);
 
#endif  // SQL_JOIN_OPTIMIZER_ESTIMATE_SELECTIVITY