Signature Description
enum class random_policy : unsigned char {
 num_rows_with_seed = 1, // Number of rows with specifying a seed
 num_rows_no_seed = 2, // Number of rows with no seed specification
 frac_rows_with_seed = 3, // Fraction of rows with specifying a seed
 frac_rows_no_seed = 4, // Fraction of rows with no seed specification
};
Specification for calling get_[data|view]_by_rand()
Number of rows means the n parameter is an positive integer specifying
the number of rows to select
Fraction of rows means the n parameter is a positive real number [0:1]
specifying a fraction of rows to select