MySQL 9.5.0
Source Code Documentation
Functions
secondary_statistics Namespace Reference

Functions

double NumDistinctValues (THD *thd, const Field &field)
 If secondary engine is available, return number of distinct values (NDV) information for specified field. More...
 

Function Documentation

◆ NumDistinctValues()

double secondary_statistics::NumDistinctValues ( THD *  thd,
const Field &  field 
)

If secondary engine is available, return number of distinct values (NDV) information for specified field.

Parameters
thdThe current thread.
fieldThe field we request NDV for
Returns
NDV if secondary engine is active and has information on column, -1.0, otherwise