Constant cost and selectivity values

The following modifiers specify a cost or selectivity value when you execute the CREATE FUNCTION statement. The cost or selectivity value does not change for each invocation of the function:
  • percall_cost=integer

    The percall_cost modifier specifies the cost of executing the function once. The integer value is a number.

  • selconst=float

    The selconst modifier specifies the selectivity of a function. The float value is a floating-point number between 0 and 1 that represents the fraction of the rows for which you expect the routine to return TRUE.